[flutter_tools] Fix _CastError in HotRunner._resetDirtyAssets (#108771)

packages/flutter_tools/lib/src/base/dds.dart

@@ -12,6 +12,7 @@ import 'context.dart';
 import 'io.dart' as io;
 import 'logger.dart';
 
+// TODO(fujino): This should be direct injected, rather than mutable global state.
 @visibleForTesting
 Future<dds.DartDevelopmentService> Function(
   Uri remoteVmServiceUri, {

packages/flutter_tools/lib/src/commands/daemon.dart

@@ -123,7 +123,7 @@ class _DaemonServer {
         // We have to listen to socket.done. Otherwise when the connection is
         // reset, we will receive an uncatchable exception.
         // https://github.com/dart-lang/sdk/issues/25518
-        final Future<void> socketDone = socket.done.catchError((dynamic error, StackTrace stackTrace) {
+        final Future<void> socketDone = socket.done.catchError((Object error, StackTrace stackTrace) {
           logger!.printError('Socket error: $error');
           logger!.printTrace('$stackTrace');
         });
@@ -145,8 +145,8 @@ class _DaemonServer {
   }
 }
 
-typedef CommandHandler = Future<dynamic>? Function(Map<String, dynamic> args);
-typedef CommandHandlerWithBinary = Future<dynamic> Function(Map<String, dynamic> args, Stream<List<int>>? binary);
+typedef CommandHandler = Future<Object?>? Function(Map<String, Object?> args);
+typedef CommandHandlerWithBinary = Future<Object?> Function(Map<String, Object?> args, Stream<List<int>>? binary);
 
 class Daemon {
   Daemon(
@@ -221,7 +221,7 @@ class Daemon {
         throw DaemonException('no domain for method: $method');
       }
 
-      _domainMap[prefix]!.handleCommand(name, id, castStringKeyedMap(request.data['params']) ?? const <String, dynamic>{}, request.binary);
+      _domainMap[prefix]!.handleCommand(name, id, castStringKeyedMap(request.data['params']) ?? const <String, Object?>{}, request.binary);
     } on Exception catch (error, trace) {
       connection.sendErrorResponse(id, _toJsonable(error), trace);
     }
@@ -268,52 +268,53 @@ abstract class Domain {
   @override
   String toString() => name;
 
-  void handleCommand(String command, Object id, Map<String, dynamic> args, Stream<List<int>>? binary) {
-    Future<dynamic>.sync(() {
+  void handleCommand(String command, Object id, Map<String, Object?> args, Stream<List<int>>? binary) {
+    Future<Object?>.sync(() {
       if (_handlers.containsKey(command)) {
         return _handlers[command]!(args);
       } else if (_handlersWithBinary.containsKey(command)) {
         return _handlersWithBinary[command]!(args, binary);
       }
       throw DaemonException('command not understood: $name.$command');
-    }).then<dynamic>((dynamic result) {
+    }).then<Object?>((Object? result) {
       daemon.connection.sendResponse(id, _toJsonable(result));
+      return null;
     }).catchError((Object error, StackTrace stackTrace) {
       daemon.connection.sendErrorResponse(id, _toJsonable(error), stackTrace);
     });
   }
 
-  void sendEvent(String name, [ dynamic args, List<int>? binary ]) {
+  void sendEvent(String name, [ Object? args, List<int>? binary ]) {
     daemon.connection.sendEvent(name, _toJsonable(args), binary);
   }
 
-  String? _getStringArg(Map<String, dynamic> args, String name, { bool required = false }) {
+  String? _getStringArg(Map<String, Object?> args, String name, { bool required = false }) {
     if (required && !args.containsKey(name)) {
       throw DaemonException('$name is required');
     }
-    final dynamic val = args[name];
+    final Object? val = args[name];
     if (val != null && val is! String) {
       throw DaemonException('$name is not a String');
     }
     return val as String?;
   }
 
-  bool? _getBoolArg(Map<String, dynamic> args, String name, { bool required = false }) {
+  bool? _getBoolArg(Map<String, Object?> args, String name, { bool required = false }) {
     if (required && !args.containsKey(name)) {
       throw DaemonException('$name is required');
     }
-    final dynamic val = args[name];
+    final Object? val = args[name];
     if (val != null && val is! bool) {
       throw DaemonException('$name is not a bool');
     }
     return val as bool?;
   }
 
-  int? _getIntArg(Map<String, dynamic> args, String name, { bool required = false }) {
+  int? _getIntArg(Map<String, Object?> args, String name, { bool required = false }) {
     if (required && !args.containsKey(name)) {
       throw DaemonException('$name is required');
     }
-    final dynamic val = args[name];
+    final Object? val = args[name];
     if (val != null && val is! int) {
       throw DaemonException('$name is not an int');
     }
@@ -334,7 +335,7 @@ class DaemonDomain extends Domain {
 
     sendEvent(
       'daemon.connected',
-      <String, dynamic>{
+      <String, Object?>{
         'version': protocolVersion,
         'pid': pid,
       },
@@ -357,13 +358,13 @@ class DaemonDomain extends Domain {
         }
       } else {
         if (message.stackTrace != null) {
-          sendEvent('daemon.logMessage', <String, dynamic>{
+          sendEvent('daemon.logMessage', <String, Object?>{
             'level': message.level,
             'message': message.message,
             'stackTrace': message.stackTrace.toString(),
           });
         } else {
-          sendEvent('daemon.logMessage', <String, dynamic>{
+          sendEvent('daemon.logMessage', <String, Object?>{
             'level': message.level,
             'message': message.message,
           });
@@ -374,7 +375,7 @@ class DaemonDomain extends Domain {
 
   StreamSubscription<LogMessage>? _subscription;
 
-  Future<String> version(Map<String, dynamic> args) {
+  Future<String> version(Map<String, Object?> args) {
     return Future<String>.value(protocolVersion);
   }
 
@@ -384,16 +385,16 @@ class DaemonDomain extends Domain {
   /// --web-allow-expose-url switch. The client may return the same URL back if
   /// tunnelling is not required for a given URL.
   Future<String> exposeUrl(String url) async {
-    final dynamic res = await daemon.connection.sendRequest('app.exposeUrl', <String, String>{'url': url});
-    if (res is Map<String, dynamic> && res['url'] is String) {
-      return res['url'] as String;
+    final Object? res = await daemon.connection.sendRequest('app.exposeUrl', <String, String>{'url': url});
+    if (res is Map<String, Object?> && res['url'] is String) {
+      return res['url']! as String;
     } else {
       globals.printError('Invalid response to exposeUrl - params should include a String url field');
       return url;
     }
   }
 
-  Future<void> shutdown(Map<String, dynamic> args) {
+  Future<void> shutdown(Map<String, Object?> args) {
     Timer.run(daemon.shutdown);
     return Future<void>.value();
   }
@@ -408,7 +409,7 @@ class DaemonDomain extends Domain {
   /// This does not filter based on the current workflow restrictions, such
   /// as whether command line tools are installed or whether the host platform
   /// is correct.
-  Future<Map<String, Object>> getSupportedPlatforms(Map<String, dynamic> args) async {
+  Future<Map<String, Object>> getSupportedPlatforms(Map<String, Object?> args) async {
     final String? projectRoot = _getStringArg(args, 'projectRoot', required: true);
     final List<String> result = <String>[];
     try {
@@ -442,7 +443,7 @@ class DaemonDomain extends Domain {
         'platforms': result,
       };
     } on Exception catch (err, stackTrace) {
-      sendEvent('log', <String, dynamic>{
+      sendEvent('log', <String, Object?>{
         'log': 'Failed to parse project metadata',
         'stackTrace': stackTrace.toString(),
         'error': true,
@@ -604,7 +605,7 @@ class AppDomain extends Domain {
     logger.domain = this;
     logger.app = app;
 
-    _sendAppEvent(app, 'start', <String, dynamic>{
+    _sendAppEvent(app, 'start', <String, Object?>{
       'deviceId': device.id,
       'directory': projectDirectory,
       'supportsRestart': isRestartSupported(enableHotReload, device),
@@ -619,7 +620,7 @@ class AppDomain extends Domain {
       // As it just writes to stdout.
       unawaited(connectionInfoCompleter.future.then<void>(
         (DebugConnectionInfo info) {
-          final Map<String, dynamic> params = <String, dynamic>{
+          final Map<String, Object?> params = <String, Object?>{
             // The web vmservice proxy does not have an http address.
             'port': info.httpUri?.port ?? info.wsUri!.port,
             'wsUri': info.wsUri.toString(),
@@ -646,7 +647,7 @@ class AppDomain extends Domain {
         );
         _sendAppEvent(app, 'stop');
       } on Exception catch (error, trace) {
-        _sendAppEvent(app, 'stop', <String, dynamic>{
+        _sendAppEvent(app, 'stop', <String, Object?>{
           'error': _toJsonable(error),
           'trace': '$trace',
         });
@@ -665,7 +666,7 @@ class AppDomain extends Domain {
 
   final int _hotReloadDebounceDurationMs = 50;
 
-  Future<OperationResult>? restart(Map<String, dynamic> args) async {
+  Future<OperationResult>? restart(Map<String, Object?> args) async {
     final String? appId = _getStringArg(args, 'appId', required: true);
     final bool fullRestart = _getBoolArg(args, 'fullRestart') ?? false;
     final bool pauseAfterRestart = _getBoolArg(args, 'pause') ?? false;
@@ -727,18 +728,18 @@ class AppDomain extends Domain {
   ///       "type":"_extensionType",
   ///       "method":"ext.flutter.platformOverride"
   ///     }
-  Future<Map<String, dynamic>> callServiceExtension(Map<String, dynamic> args) async {
+  Future<Map<String, Object?>> callServiceExtension(Map<String, Object?> args) async {
     final String? appId = _getStringArg(args, 'appId', required: true);
     final String methodName = _getStringArg(args, 'methodName')!;
-    final Map<String, dynamic>? params = args['params'] == null ? <String, dynamic>{} : castStringKeyedMap(args['params']);
+    final Map<String, Object?>? params = args['params'] == null ? <String, Object?>{} : castStringKeyedMap(args['params']);
 
     final AppInstance? app = _getApp(appId);
     if (app == null) {
       throw DaemonException("app '$appId' not found");
     }
-    final FlutterDevice device = app.runner!.flutterDevices.first!;
+    final FlutterDevice device = app.runner!.flutterDevices.first;
     final List<FlutterView> views = await device.vmService!.getFlutterViews();
-    final Map<String, dynamic>? result = await device
+    final Map<String, Object?>? result = await device
       .vmService!
       .invokeFlutterExtensionRpcRaw(
         methodName,
@@ -752,13 +753,13 @@ class AppDomain extends Domain {
 
     if (result.containsKey('error')) {
       // ignore: only_throw_errors
-      throw result['error']! as Object;
+      throw result['error']!;
     }
 
     return result;
   }
 
-  Future<bool> stop(Map<String, dynamic> args) async {
+  Future<bool> stop(Map<String, Object?> args) async {
     final String? appId = _getStringArg(args, 'appId', required: true);
 
     final AppInstance? app = _getApp(appId);
@@ -768,8 +769,8 @@ class AppDomain extends Domain {
 
     return app.stop().then<bool>(
       (void value) => true,
-      onError: (dynamic error, StackTrace stack) {
-        _sendAppEvent(app, 'log', <String, dynamic>{'log': '$error', 'error': true});
+      onError: (Object? error, StackTrace stack) {
+        _sendAppEvent(app, 'log', <String, Object?>{'log': '$error', 'error': true});
         app.closeLogger();
         _apps.remove(app);
         return false;
@@ -777,7 +778,7 @@ class AppDomain extends Domain {
     );
   }
 
-  Future<bool> detach(Map<String, dynamic> args) async {
+  Future<bool> detach(Map<String, Object?> args) async {
     final String? appId = _getStringArg(args, 'appId', required: true);
 
     final AppInstance? app = _getApp(appId);
@@ -787,8 +788,8 @@ class AppDomain extends Domain {
 
     return app.detach().then<bool>(
       (void value) => true,
-      onError: (dynamic error, StackTrace stack) {
-        _sendAppEvent(app, 'log', <String, dynamic>{'log': '$error', 'error': true});
+      onError: (Object? error, StackTrace stack) {
+        _sendAppEvent(app, 'log', <String, Object?>{'log': '$error', 'error': true});
         app.closeLogger();
         _apps.remove(app);
         return false;
@@ -805,8 +806,8 @@ class AppDomain extends Domain {
     return null;
   }
 
-  void _sendAppEvent(AppInstance app, String name, [ Map<String, dynamic>? args ]) {
-    sendEvent('app.$name', <String, dynamic>{
+  void _sendAppEvent(AppInstance app, String name, [ Map<String, Object?>? args ]) {
+    sendEvent('app.$name', <String, Object?>{
       'appId': app.id,
       ...?args,
     });
@@ -876,8 +877,8 @@ class DeviceDomain extends Domain {
 
   /// Return a list of the current devices, with each device represented as a map
   /// of properties (id, name, platform, ...).
-  Future<List<Map<String, dynamic>>> getDevices([ Map<String, dynamic>? args ]) async {
-    return <Map<String, dynamic>>[
+  Future<List<Map<String, Object?>>> getDevices([ Map<String, Object?>? args ]) async {
+    return <Map<String, Object?>>[
       for (final PollingDeviceDiscovery discoverer in _discoverers)
         for (final Device device in await discoverer.devices)
           await _deviceToMap(device),
@@ -885,8 +886,8 @@ class DeviceDomain extends Domain {
   }
 
   /// Return a list of the current devices, discarding existing cache of devices.
-  Future<List<Map<String, dynamic>>> discoverDevices([ Map<String, dynamic>? args ]) async {
-    return <Map<String, dynamic>>[
+  Future<List<Map<String, Object?>>> discoverDevices([ Map<String, Object?>? args ]) async {
+    return <Map<String, Object?>>[
       for (final PollingDeviceDiscovery discoverer in _discoverers)
         for (final Device device in await discoverer.discoverDevices())
           await _deviceToMap(device),
@@ -894,21 +895,21 @@ class DeviceDomain extends Domain {
   }
 
   /// Enable device events.
-  Future<void> enable(Map<String, dynamic> args) async {
+  Future<void> enable(Map<String, Object?> args) async {
     for (final PollingDeviceDiscovery discoverer in _discoverers) {
       discoverer.startPolling();
     }
   }
 
   /// Disable device events.
-  Future<void> disable(Map<String, dynamic> args) async {
+  Future<void> disable(Map<String, Object?> args) async {
     for (final PollingDeviceDiscovery discoverer in _discoverers) {
       discoverer.stopPolling();
     }
   }
 
   /// Forward a host port to a device port.
-  Future<Map<String, dynamic>> forward(Map<String, dynamic> args) async {
+  Future<Map<String, Object?>> forward(Map<String, Object?> args) async {
     final String? deviceId = _getStringArg(args, 'deviceId', required: true);
     final int devicePort = _getIntArg(args, 'devicePort', required: true)!;
     int? hostPort = _getIntArg(args, 'hostPort');
@@ -920,11 +921,11 @@ class DeviceDomain extends Domain {
 
     hostPort = await device.portForwarder!.forward(devicePort, hostPort: hostPort);
 
-    return <String, dynamic>{'hostPort': hostPort};
+    return <String, Object?>{'hostPort': hostPort};
   }
 
   /// Removes a forwarded port.
-  Future<void> unforward(Map<String, dynamic> args) async {
+  Future<void> unforward(Map<String, Object?> args) async {
     final String? deviceId = _getStringArg(args, 'deviceId', required: true);
     final int devicePort = _getIntArg(args, 'devicePort', required: true)!;
     final int hostPort = _getIntArg(args, 'hostPort', required: true)!;
@@ -938,7 +939,7 @@ class DeviceDomain extends Domain {
   }
 
   /// Returns whether a device supports runtime mode.
-  Future<bool> supportsRuntimeMode(Map<String, dynamic> args) async {
+  Future<bool> supportsRuntimeMode(Map<String, Object?> args) async {
     final String? deviceId = _getStringArg(args, 'deviceId', required: true);
     final Device? device = await daemon.deviceDomain._getDevice(deviceId);
     if (device == null) {
@@ -949,7 +950,7 @@ class DeviceDomain extends Domain {
   }
 
   /// Creates an application package from a file in the temp directory.
-  Future<String> uploadApplicationPackage(Map<String, dynamic> args) async {
+  Future<String> uploadApplicationPackage(Map<String, Object?> args) async {
     final TargetPlatform targetPlatform = getTargetPlatformForName(_getStringArg(args, 'targetPlatform', required: true)!);
     final File applicationBinary = daemon.proxyDomain.tempDirectory.childFile(_getStringArg(args, 'applicationBinary', required: true)!);
     final ApplicationPackage? applicationPackage = await ApplicationPackageFactory.instance!.getPackageForPlatform(
@@ -962,7 +963,7 @@ class DeviceDomain extends Domain {
   }
 
   /// Starts the log reader on the device.
-  Future<String> startLogReader(Map<String, dynamic> args) async {
+  Future<String> startLogReader(Map<String, Object?> args) async {
     final String? deviceId = _getStringArg(args, 'deviceId', required: true);
     final Device? device = await daemon.deviceDomain._getDevice(deviceId);
     if (device == null) {
@@ -981,13 +982,13 @@ class DeviceDomain extends Domain {
   }
 
   /// Stops a log reader that was previously started.
-  Future<void> stopLogReader(Map<String, dynamic> args) async {
+  Future<void> stopLogReader(Map<String, Object?> args) async {
     final String? id = _getStringArg(args, 'id', required: true);
     _logReaders.remove(id)?.dispose();
   }
 
   /// Starts an app on a device.
-  Future<Map<String, dynamic>> startApp(Map<String, dynamic> args) async {
+  Future<Map<String, Object?>> startApp(Map<String, Object?> args) async {
     final String? deviceId = _getStringArg(args, 'deviceId', required: true);
     final Device? device = await daemon.deviceDomain._getDevice(deviceId);
     if (device == null) {
@@ -1010,14 +1011,14 @@ class DeviceDomain extends Domain {
       ipv6: _getBoolArg(args, 'ipv6') ?? false,
       userIdentifier: _getStringArg(args, 'userIdentifier'),
     );
-    return <String, dynamic>{
+    return <String, Object?>{
       'started': result.started,
       'observatoryUri': result.observatoryUri?.toString(),
     };
   }
 
   /// Stops an app.
-  Future<bool> stopApp(Map<String, dynamic> args) async {
+  Future<bool> stopApp(Map<String, Object?> args) async {
     final String? deviceId = _getStringArg(args, 'deviceId', required: true);
     final Device? device = await daemon.deviceDomain._getDevice(deviceId);
     if (device == null) {
@@ -1032,7 +1033,7 @@ class DeviceDomain extends Domain {
   }
 
   /// Takes a screenshot.
-  Future<String?> takeScreenshot(Map<String, dynamic> args) async {
+  Future<String?> takeScreenshot(Map<String, Object?> args) async {
     final String? deviceId = _getStringArg(args, 'deviceId', required: true);
     final Device? device = await daemon.deviceDomain._getDevice(deviceId);
     if (device == null) {
@@ -1082,10 +1083,10 @@ class DevToolsDomain extends Domain {
 
   DevtoolsLauncher? _devtoolsLauncher;
 
-  Future<Map<String, dynamic>> serve([ Map<String, dynamic>? args ]) async {
+  Future<Map<String, Object?>> serve([ Map<String, Object?>? args ]) async {
     _devtoolsLauncher ??= DevtoolsLauncher.instance;
     final DevToolsServerAddress? server = await _devtoolsLauncher?.serve();
-    return<String, dynamic>{
+    return<String, Object?>{
       'host': server?.host,
       'port': server?.port,
     };
@@ -1097,8 +1098,8 @@ class DevToolsDomain extends Domain {
   }
 }
 
-Future<Map<String, dynamic>> _deviceToMap(Device device) async {
-  return <String, dynamic>{
+Future<Map<String, Object?>> _deviceToMap(Device device) async {
+  return <String, Object?>{
     'id': device.id,
     'name': device.name,
     'platform': getNameForTargetPlatform(await device.targetPlatform),
@@ -1120,8 +1121,8 @@ Future<Map<String, dynamic>> _deviceToMap(Device device) async {
   };
 }
 
-Map<String, dynamic> _emulatorToMap(Emulator emulator) {
-  return <String, dynamic>{
+Map<String, Object?> _emulatorToMap(Emulator emulator) {
+  return <String, Object?>{
     'id': emulator.id,
     'name': emulator.name,
     'category': emulator.category.toString(),
@@ -1129,15 +1130,15 @@ Map<String, dynamic> _emulatorToMap(Emulator emulator) {
   };
 }
 
-Map<String, dynamic> _operationResultToMap(OperationResult result) {
-  return <String, dynamic>{
+Map<String, Object?> _operationResultToMap(OperationResult result) {
+  return <String, Object?>{
     'code': result.code,
     'message': result.message,
   };
 }
 
-Object? _toJsonable(dynamic obj) {
-  if (obj is String || obj is int || obj is bool || obj is Map<dynamic, dynamic> || obj is List<dynamic> || obj == null) {
+Object? _toJsonable(Object? obj) {
+  if (obj is String || obj is int || obj is bool || obj is Map<Object?, Object?> || obj is List<Object?> || obj == null) {
     return obj;
   }
   if (obj is OperationResult) {
@@ -1250,7 +1251,7 @@ class NotifyingLogger extends DelegatingLogger {
   }
 
   @override
-  void sendEvent(String name, [Map<String, dynamic>? args]) { }
+  void sendEvent(String name, [Map<String, Object?>? args]) { }
 
   @override
   bool get supportsColor => throw UnimplementedError();
@@ -1305,12 +1306,12 @@ class EmulatorDomain extends Domain {
     androidWorkflow: androidWorkflow!,
   );
 
-  Future<List<Map<String, dynamic>>> getEmulators([ Map<String, dynamic>? args ]) async {
+  Future<List<Map<String, Object?>>> getEmulators([ Map<String, Object?>? args ]) async {
     final List<Emulator> list = await emulators.getAllAvailableEmulators();
-    return list.map<Map<String, dynamic>>(_emulatorToMap).toList();
+    return list.map<Map<String, Object?>>(_emulatorToMap).toList();
   }
 
-  Future<void> launch(Map<String, dynamic> args) async {
+  Future<void> launch(Map<String, Object?> args) async {
     final String emulatorId = _getStringArg(args, 'emulatorId', required: true)!;
     final bool coldBoot = _getBoolArg(args, 'coldBoot') ?? false;
     final List<Emulator> matches =
@@ -1324,10 +1325,10 @@ class EmulatorDomain extends Domain {
     }
   }
 
-  Future<Map<String, dynamic>> create(Map<String, dynamic> args) async {
+  Future<Map<String, Object?>> create(Map<String, Object?> args) async {
     final String? name = _getStringArg(args, 'name');
     final CreateEmulatorResult res = await emulators.createEmulator(name: name);
-    return <String, dynamic>{
+    return <String, Object?>{
       'success': res.success,
       'emulatorName': res.emulatorName,
       'error': res.error,
@@ -1349,7 +1350,7 @@ class ProxyDomain extends Domain {
   int _id = 0;
 
   /// Writes to a file in a local temporary directory.
-  Future<void> writeTempFile(Map<String, dynamic> args, Stream<List<int>>? binary) async {
+  Future<void> writeTempFile(Map<String, Object?> args, Stream<List<int>>? binary) async {
     final String path = _getStringArg(args, 'path', required: true)!;
     final File file = tempDirectory.childFile(path);
     await file.parent.create(recursive: true);
@@ -1357,7 +1358,7 @@ class ProxyDomain extends Domain {
   }
 
   /// Calculate rolling hashes for a file in the local temporary directory.
-  Future<Map<String, dynamic>?> calculateFileHashes(Map<String, dynamic> args) async {
+  Future<Map<String, Object?>?> calculateFileHashes(Map<String, Object?> args) async {
     final String path = _getStringArg(args, 'path', required: true)!;
     final File file = tempDirectory.childFile(path);
     if (!await file.exists()) {
@@ -1367,20 +1368,20 @@ class ProxyDomain extends Domain {
     return result.toJson();
   }
 
-  Future<bool?> updateFile(Map<String, dynamic> args, Stream<List<int>>? binary) async {
+  Future<bool?> updateFile(Map<String, Object?> args, Stream<List<int>>? binary) async {
     final String path = _getStringArg(args, 'path', required: true)!;
     final File file = tempDirectory.childFile(path);
     if (!await file.exists()) {
       return null;
     }
-    final List<Map<String, dynamic>> deltaJson = (args['delta'] as List<dynamic>).cast<Map<String, dynamic>>();
+    final List<Map<String, Object?>> deltaJson = (args['delta']! as List<Object?>).cast<Map<String, Object?>>();
     final List<FileDeltaBlock> delta = FileDeltaBlock.fromJsonList(deltaJson);
     final bool result = await FileTransfer().rebuildFile(file, delta, binary!);
     return result;
   }
 
   /// Opens a connection to a local port, and returns the connection id.
-  Future<String> connect(Map<String, dynamic> args) async {
+  Future<String> connect(Map<String, Object?> args) async {
     final int targetPort = _getIntArg(args, 'port', required: true)!;
     final String id = 'portForwarder_${targetPort}_${_id++}';
 
@@ -1406,22 +1407,22 @@ class ProxyDomain extends Domain {
     _forwardedConnections[id] = socket;
     socket.listen((List<int> data) {
       sendEvent('proxy.data.$id', null, data);
-    }, onError: (dynamic error, StackTrace stackTrace) {
+    }, onError: (Object error, StackTrace stackTrace) {
       // Socket error, probably disconnected.
       globals.logger.printTrace('Socket error: $error, $stackTrace');
     });
 
-    unawaited(socket.done.catchError((dynamic error, StackTrace stackTrace) {
+    unawaited(socket.done.catchError((Object error, StackTrace stackTrace) {
       // Socket error, probably disconnected.
       globals.logger.printTrace('Socket error: $error, $stackTrace');
-    }).then((dynamic _) {
+    }).then((Object? _) {
       sendEvent('proxy.disconnected.$id');
     }));
     return id;
   }
 
   /// Disconnects from a previously established connection.
-  Future<bool> disconnect(Map<String, dynamic> args) async {
+  Future<bool> disconnect(Map<String, Object?> args) async {
     final String? id = _getStringArg(args, 'id', required: true);
     if (_forwardedConnections.containsKey(id)) {
       await _forwardedConnections.remove(id)?.close();
@@ -1431,7 +1432,7 @@ class ProxyDomain extends Domain {
   }
 
   /// Writes to a previously established connection.
-  Future<bool> write(Map<String, dynamic> args, Stream<List<int>>? binary) async {
+  Future<bool> write(Map<String, Object?> args, Stream<List<int>>? binary) async {
     final String? id = _getStringArg(args, 'id', required: true);
     if (_forwardedConnections.containsKey(id)) {
       final StreamSubscription<List<int>> subscription = binary!.listen(_forwardedConnections[id!]!.add);
@@ -1519,7 +1520,7 @@ class AppRunLogger extends DelegatingLogger {
         printStatus(message);
       }
     } else {
-      final Map<String, dynamic> event = <String, dynamic>{
+      final Map<String, Object?> event = <String, Object?>{
         'id': eventId,
         'progressId': eventType,
         if (message != null) 'message': message,
@@ -1531,7 +1532,7 @@ class AppRunLogger extends DelegatingLogger {
   }
 
   @override
-  void sendEvent(String name, [Map<String, dynamic>? args, List<int>? binary]) {
+  void sendEvent(String name, [Map<String, Object?>? args, List<int>? binary]) {
     if (domain == null) {
       printStatus('event sent after app closed: $name');
     } else {

packages/flutter_tools/lib/src/isolated/resident_web_runner.dart

@@ -81,14 +81,14 @@ const String kExitMessage = 'Failed to establish connection with the application
 
 class ResidentWebRunner extends ResidentRunner {
   ResidentWebRunner(
-    FlutterDevice? device, {
+    FlutterDevice device, {
     String? target,
     bool stayResident = true,
     bool machine = false,
     required this.flutterProject,
     required bool? ipv6,
     required DebuggingOptions debuggingOptions,
-    required FileSystem? fileSystem,
+    required FileSystem fileSystem,
     required Logger? logger,
     required SystemClock systemClock,
     required Usage usage,
@@ -100,8 +100,8 @@ class ResidentWebRunner extends ResidentRunner {
        _usage = usage,
        _urlTunneller = urlTunneller,
        super(
-          <FlutterDevice?>[device],
-          target: target ?? fileSystem!.path.join('lib', 'main.dart'),
+          <FlutterDevice>[device],
+          target: target ?? fileSystem.path.join('lib', 'main.dart'),
           debuggingOptions: debuggingOptions,
           ipv6: ipv6,
           stayResident: stayResident,
@@ -109,7 +109,7 @@ class ResidentWebRunner extends ResidentRunner {
           devtoolsHandler: devtoolsHandler,
         );
 
-  final FileSystem? _fileSystem;
+  final FileSystem _fileSystem;
   final Logger? _logger;
   final SystemClock _systemClock;
   final Usage _usage;
@@ -119,7 +119,7 @@ class ResidentWebRunner extends ResidentRunner {
   Logger? get logger => _logger;
 
   @override
-  FileSystem? get fileSystem => _fileSystem;
+  FileSystem get fileSystem => _fileSystem;
 
   FlutterDevice? get device => flutterDevices.first;
   final FlutterProject flutterProject;
@@ -245,7 +245,7 @@ class ResidentWebRunner extends ResidentRunner {
     }
     final String modeName = debuggingOptions.buildInfo.friendlyModeName;
     _logger!.printStatus(
-      'Launching ${getDisplayPath(target, _fileSystem!)} '
+      'Launching ${getDisplayPath(target, _fileSystem)} '
       'on ${device!.device!.name} in $modeName mode...',
     );
     if (device!.device is ChromiumDevice) {
@@ -271,7 +271,7 @@ class ResidentWebRunner extends ResidentRunner {
           buildInfo: debuggingOptions.buildInfo,
           enableDwds: _enableDwds,
           enableDds: debuggingOptions.enableDds,
-          entrypoint: _fileSystem!.file(target).uri,
+          entrypoint: _fileSystem.file(target).uri,
           expressionCompiler: expressionCompiler,
           chromiumLauncher: _chromiumLauncher,
           nullAssertions: debuggingOptions.nullAssertions,
@@ -425,7 +425,7 @@ class ResidentWebRunner extends ResidentRunner {
   Future<Uri> _generateEntrypoint(Uri mainUri, PackageConfig? packageConfig) async {
     File? result = _generatedEntrypointDirectory?.childFile('web_entrypoint.dart');
     if (_generatedEntrypointDirectory == null) {
-      _generatedEntrypointDirectory ??= _fileSystem!.systemTempDirectory.createTempSync('flutter_tools.')
+      _generatedEntrypointDirectory ??= _fileSystem.systemTempDirectory.createTempSync('flutter_tools.')
         ..createSync();
       result = _generatedEntrypointDirectory!.childFile('web_entrypoint.dart');
 
@@ -438,16 +438,17 @@ class ResidentWebRunner extends ResidentRunner {
       Uri? importedEntrypoint = packageConfig!.toPackageUri(mainUri);
       // Special handling for entrypoints that are not under lib, such as test scripts.
       if (importedEntrypoint == null) {
-        final String parent = _fileSystem!.file(mainUri).parent.path;
-        flutterDevices.first!.generator!.addFileSystemRoot(parent);
-        flutterDevices.first!.generator!.addFileSystemRoot(_fileSystem!.directory('test').absolute.path);
+        final String parent = _fileSystem.file(mainUri).parent.path;
+        flutterDevices.first.generator!
+          ..addFileSystemRoot(parent)
+          ..addFileSystemRoot(_fileSystem.directory('test').absolute.path);
         importedEntrypoint = Uri(
           scheme: 'org-dartlang-app',
           path: '/${mainUri.pathSegments.last}',
         );
       }
       final LanguageVersion languageVersion = determineLanguageVersion(
-        _fileSystem!.file(mainUri),
+        _fileSystem.file(mainUri),
         packageConfig[flutterProject.manifest.appName],
         Cache.flutterRoot!,
       );
@@ -487,7 +488,7 @@ class ResidentWebRunner extends ResidentRunner {
     );
     final UpdateFSReport report = await device!.devFS!.update(
       mainUri: await _generateEntrypoint(
-        _fileSystem!.file(mainPath).absolute.uri,
+        _fileSystem.file(mainPath).absolute.uri,
         invalidationResult.packageConfig,
       ),
       target: target,
@@ -603,7 +604,7 @@ class ResidentWebRunner extends ResidentRunner {
     }
     if (websocketUri != null) {
       if (debuggingOptions.vmserviceOutFile != null) {
-        _fileSystem!.file(debuggingOptions.vmserviceOutFile)
+        _fileSystem.file(debuggingOptions.vmserviceOutFile)
           ..createSync(recursive: true)
           ..writeAsStringSync(websocketUri.toString());
       }

packages/flutter_tools/lib/src/resident_runner.dart

@@ -240,7 +240,7 @@ class FlutterDevice {
     bool cacheStartupProfile = false,
     bool enableDds = true,
     required bool allowExistingDdsInstance,
-    bool? ipv6 = false,
+    bool ipv6 = false,
   }) {
     final Completer<void> completer = Completer<void>();
     late StreamSubscription<void> subscription;
@@ -927,14 +927,14 @@ abstract class ResidentHandlers {
     if (!supportsWriteSkSL) {
       throw Exception('writeSkSL is not supported by this runner.');
     }
-    final List<FlutterView> views = await flutterDevices
-      .first!
-      .vmService!.getFlutterViews();
-    final Map<String, Object> data = await (flutterDevices.first!.vmService!.getSkSLs(
+    final FlutterDevice flutterDevice = flutterDevices.first!;
+    final FlutterVmService vmService = flutterDevice.vmService!;
+    final List<FlutterView> views = await vmService.getFlutterViews();
+    final Map<String, Object?>? data = await vmService.getSkSLs(
       viewId: views.first.id,
-    ) as FutureOr<Map<String, Object>>);
-    final Device device = flutterDevices.first!.device!;
-    return sharedSkSlWriter(device, data);
+    );
+    final Device device = flutterDevice.device!;
+    return sharedSkSlWriter(device, data!);
   }
 
   /// Take a screenshot on the provided [device].
@@ -1091,10 +1091,10 @@ abstract class ResidentRunner extends ResidentHandlers {
   Logger? get logger => globals.logger;
 
   @override
-  FileSystem? get fileSystem => globals.fs;
+  FileSystem get fileSystem => globals.fs;
 
   @override
-  final List<FlutterDevice?> flutterDevices;
+  final List<FlutterDevice> flutterDevices;
 
   final String target;
   final DebuggingOptions debuggingOptions;
@@ -1171,7 +1171,7 @@ abstract class ResidentRunner extends ResidentHandlers {
   //
   // Would be null if there is no device connected or
   // there is no devFS associated with the first device.
-  Uri? get uri => flutterDevices.first?.devFS?.baseUri;
+  Uri? get uri => flutterDevices.first.devFS?.baseUri;
 
   /// Returns [true] if the resident runner exited after invoking [exit()].
   bool get exited => _exited;
@@ -1257,7 +1257,7 @@ abstract class ResidentRunner extends ResidentHandlers {
   void writeVmServiceFile() {
     if (debuggingOptions.vmserviceOutFile != null) {
       try {
-        final String address = flutterDevices.first!.vmService!.wsAddress.toString();
+        final String address = flutterDevices.first.vmService!.wsAddress.toString();
         final File vmserviceOutFile = globals.fs.file(debuggingOptions.vmserviceOutFile);
         vmserviceOutFile.createSync(recursive: true);
         vmserviceOutFile.writeAsStringSync(address);
@@ -1359,7 +1359,7 @@ abstract class ResidentRunner extends ResidentHandlers {
         hostVmServicePort: debuggingOptions.hostVmServicePort,
         getSkSLMethod: getSkSLMethod,
         printStructuredErrorLogMethod: printStructuredErrorLog,
-        ipv6: ipv6,
+        ipv6: ipv6 ?? false,
         disableServiceAuthCodes: debuggingOptions.disableServiceAuthCodes,
         cacheStartupProfile: debuggingOptions.cacheStartupProfile,
       );

packages/flutter_tools/lib/src/run_cold.dart

@@ -88,11 +88,11 @@ class ColdRunner extends ResidentRunner {
       ));
     }
 
-    if (flutterDevices.first!.observatoryUris != null) {
+    if (flutterDevices.first.observatoryUris != null) {
       // For now, only support one debugger connection.
       connectionInfoCompleter?.complete(DebugConnectionInfo(
-        httpUri: flutterDevices.first!.vmService!.httpAddress,
-        wsUri: flutterDevices.first!.vmService!.wsAddress,
+        httpUri: flutterDevices.first.vmService!.httpAddress,
+        wsUri: flutterDevices.first.vmService!.wsAddress,
       ));
     }
 
@@ -108,7 +108,7 @@ class ColdRunner extends ResidentRunner {
 
     if (traceStartup) {
       // Only trace startup for the first device.
-      final FlutterDevice device = flutterDevices.first!;
+      final FlutterDevice device = flutterDevices.first;
       if (device.vmService != null) {
         globals.printStatus('Tracing startup on ${device.device!.name}.');
         final String outputPath = globals.platform.environment[kFlutterTestOutputsDirEnvName] ?? getBuildDirectory();

packages/flutter_tools/lib/src/run_hot.dart

@@ -141,7 +141,7 @@ class HotRunner extends ResidentRunner {
     }
 
     if (flutterDevices.length == 1) {
-      final Device device = flutterDevices.first!.device!;
+      final Device device = flutterDevices.first.device!;
       _targetPlatform = getNameForTargetPlatform(await device.targetPlatform);
       _sdkName = await device.sdkNameAndVersion;
       _emulator = await device.isLocalEmulator;
@@ -257,8 +257,8 @@ class HotRunner extends ResidentRunner {
         // Only handle one debugger connection.
         connectionInfoCompleter.complete(
           DebugConnectionInfo(
-            httpUri: flutterDevices.first!.vmService!.httpAddress,
-            wsUri: flutterDevices.first!.vmService!.wsAddress,
+            httpUri: flutterDevices.first.vmService!.httpAddress,
+            wsUri: flutterDevices.first.vmService!.wsAddress,
             baseUri: baseUris.first.toString(),
           ),
         );
@@ -454,12 +454,13 @@ class HotRunner extends ResidentRunner {
     }
 
     final Stopwatch findInvalidationTimer = _stopwatchFactory.createStopwatch('updateDevFS')..start();
+    final DevFS devFS = flutterDevices[0].devFS!;
     final InvalidationResult invalidationResult = await projectFileInvalidator.findInvalidated(
-      lastCompiled: flutterDevices[0]!.devFS!.lastCompiled,
-      urisToMonitor: flutterDevices[0]!.devFS!.sources,
+      lastCompiled: devFS.lastCompiled,
+      urisToMonitor: devFS.sources,
       packagesPath: packagesFilePath,
       asyncScanning: hotRunnerConfig!.asyncScanning,
-      packageConfig: flutterDevices[0]!.devFS!.lastPackageConfig
+      packageConfig: devFS.lastPackageConfig
           ?? debuggingOptions.buildInfo.packageConfig,
     );
     findInvalidationTimer.stop();
@@ -474,7 +475,7 @@ class HotRunner extends ResidentRunner {
     }
     final UpdateFSReport results = UpdateFSReport(
       success: true,
-      scannedSourcesCount: flutterDevices[0]!.devFS!.sources.length,
+      scannedSourcesCount: devFS.sources.length,
       findInvalidatedDuration: findInvalidationTimer.elapsed,
     );
     for (final FlutterDevice? device in flutterDevices) {
@@ -497,21 +498,27 @@ class HotRunner extends ResidentRunner {
   }
 
   void _resetDirtyAssets() {
-    for (final FlutterDevice? device in flutterDevices) {
-      device!.devFS!.assetPathsToEvict.clear();
-      device.devFS!.shaderPathsToEvict.clear();
+    for (final FlutterDevice device in flutterDevices) {
+      final DevFS? devFS = device.devFS;
+      if (devFS == null) {
+        // This is sometimes null, however we don't know why and have not been
+        // able to reproduce, https://github.com/flutter/flutter/issues/108653
+        continue;
+      }
+      devFS.assetPathsToEvict.clear();
+      devFS.shaderPathsToEvict.clear();
     }
   }
 
   Future<void> _cleanupDevFS() async {
     final List<Future<void>> futures = <Future<void>>[];
-    for (final FlutterDevice? device in flutterDevices) {
-      if (device!.devFS != null) {
+    for (final FlutterDevice device in flutterDevices) {
+      if (device.devFS != null) {
         // Cleanup the devFS, but don't wait indefinitely.
         // We ignore any errors, because it's not clear what we would do anyway.
         futures.add(device.devFS!.destroy()
           .timeout(const Duration(milliseconds: 250))
-          .catchError((dynamic error) {
+          .catchError((Object? error) {
             globals.printTrace('Ignored error while cleaning up DevFS: $error');
           }));
       }
@@ -756,7 +763,7 @@ class HotRunner extends ResidentRunner {
     String? restartEvent;
     try {
       final Stopwatch restartTimer = _stopwatchFactory.createStopwatch('fullRestartHelper')..start();
-      if (!(await (hotRunnerConfig!.setupHotRestart() as FutureOr<bool>))) {
+      if ((await hotRunnerConfig!.setupHotRestart()) != true) {
         return OperationResult(1, 'setupHotRestart failed');
       }
       result = await _restartFromSources(reason: reason);
@@ -885,7 +892,7 @@ class HotRunner extends ResidentRunner {
     }
 
     final Stopwatch reloadTimer = _stopwatchFactory.createStopwatch('reloadSources:reload')..start();
-    if (!(await (hotRunnerConfig!.setupHotReload() as FutureOr<bool>))) {
+    if ((await hotRunnerConfig!.setupHotReload()) != true) {
       return OperationResult(1, 'setupHotReload failed');
     }
     final Stopwatch devFSTimer = Stopwatch()..start();

packages/flutter_tools/lib/src/sksl_writer.dart

@@ -13,7 +13,7 @@ import 'convert.dart';
 import 'device.dart';
 import 'globals.dart' as globals;
 
-Future<String?> sharedSkSlWriter(Device device, Map<String, Object> data, {
+Future<String?> sharedSkSlWriter(Device device, Map<String, Object?> data, {
   File? outputFile,
   Logger? logger,
 }) async {

packages/flutter_tools/lib/src/vmservice.dart

@@ -493,7 +493,7 @@ class FlutterVmService {
   ///
   /// This method will only return data if `--cache-sksl` was provided as a
   /// flutter run argument, and only then on physical devices.
-  Future<Map<String, Object>?> getSkSLs({
+  Future<Map<String, Object?>?> getSkSLs({
     required String viewId,
   }) async {
     final vm_service.Response? response = await callMethodWrapper(
@@ -505,7 +505,7 @@ class FlutterVmService {
     if (response == null) {
       return null;
     }
-    return response.json?['SkSLs'] as Map<String, Object>?;
+    return response.json?['SkSLs'] as Map<String, Object?>?;
   }
 
   /// Flush all tasks on the UI thread for an attached Flutter view.

packages/flutter_tools/test/general.shard/resident_runner_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:async';
 
 import 'package:dds/dds.dart' as dds;
@@ -35,7 +33,6 @@ import 'package:flutter_tools/src/run_cold.dart';
 import 'package:flutter_tools/src/run_hot.dart';
 import 'package:flutter_tools/src/version.dart';
 import 'package:flutter_tools/src/vmservice.dart';
-import 'package:meta/meta.dart';
 import 'package:package_config/package_config.dart';
 import 'package:test/fake.dart';
 import 'package:vm_service/vm_service.dart' as vm_service;
@@ -157,12 +154,12 @@ const FakeVmServiceRequest evictShader = FakeVmServiceRequest(
 final Uri testUri = Uri.parse('foo://bar');
 
 void main() {
-  Testbed testbed;
-  FakeFlutterDevice flutterDevice;
-  FakeDevFS devFS;
-  ResidentRunner residentRunner;
-  FakeDevice device;
-  FakeVmServiceHost fakeVmServiceHost;
+  late Testbed testbed;
+  late FakeFlutterDevice flutterDevice;
+  late FakeDevFS devFS;
+  late ResidentRunner residentRunner;
+  late FakeDevice device;
+  FakeVmServiceHost? fakeVmServiceHost;
 
   setUp(() {
     testbed = Testbed(setup: () {
@@ -197,7 +194,7 @@ void main() {
     ]);
     final Completer<DebugConnectionInfo> futureConnectionInfo = Completer<DebugConnectionInfo>.sync();
     final Completer<void> futureAppStart = Completer<void>.sync();
-    final Future<int> result = residentRunner.attach(
+    final Future<int?> result = residentRunner.attach(
       appStartedCompleter: futureAppStart,
       connectionInfoCompleter: futureConnectionInfo,
       enableDevTools: true,
@@ -208,7 +205,7 @@ void main() {
     expect(futureConnectionInfo.isCompleted, true);
     expect((await connectionInfo).baseUri, 'foo://bar');
     expect(futureAppStart.isCompleted, true);
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }));
 
   testUsingContext('ResidentRunner suppresses errors for the initial compilation', () => testbed.run(() async {
@@ -233,7 +230,7 @@ void main() {
 
     expect(await residentRunner.run(enableDevTools: true), 0);
     expect(residentCompiler.didSuppressErrors, true);
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }));
 
   // Regression test for https://github.com/flutter/flutter/issues/60613
@@ -325,7 +322,7 @@ void main() {
 
     expect(await residentRunner.run(enableDevTools: true), 0);
     expect(residentCompiler.didSuppressErrors, false);
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }));
 
   testUsingContext('ResidentRunner can attach to device successfully with --fast-start', () => testbed.run(() async {
@@ -335,14 +332,14 @@ void main() {
       listViews,
       FakeVmServiceRequest(
         method: 'getIsolate',
-        args: <String, Object>{
+        args: <String, Object?>{
           'isolateId': fakeUnpausedIsolate.id,
         },
         jsonResponse: fakeUnpausedIsolate.toJson(),
       ),
       FakeVmServiceRequest(
         method: 'getVM',
-        jsonResponse: vm_service.VM.parse(<String, Object>{}).toJson(),
+        jsonResponse: vm_service.VM.parse(<String, Object>{})!.toJson(),
       ),
       listViews,
       const FakeVmServiceRequest(
@@ -382,7 +379,7 @@ void main() {
     );
     final Completer<DebugConnectionInfo> futureConnectionInfo = Completer<DebugConnectionInfo>.sync();
     final Completer<void> futureAppStart = Completer<void>.sync();
-    final Future<int> result = residentRunner.attach(
+    final Future<int?> result = residentRunner.attach(
       appStartedCompleter: futureAppStart,
       connectionInfoCompleter: futureConnectionInfo,
       enableDevTools: true,
@@ -393,7 +390,7 @@ void main() {
     expect(futureConnectionInfo.isCompleted, true);
     expect((await connectionInfo).baseUri, 'foo://bar');
     expect(futureAppStart.isCompleted, true);
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }));
 
   testUsingContext('ResidentRunner can handle an RPC exception from hot reload', () => testbed.run(() async {
@@ -424,7 +421,7 @@ void main() {
         fastReassemble: false,
       )),
     ));
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }, overrides: <Type, Generator>{
     Usage: () => TestUsage(),
   }));
@@ -447,7 +444,7 @@ void main() {
     expect(result.fatal, false);
     expect(result.code, 1);
     expect(result.message, contains('Device initialization has not completed.'));
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }));
 
   testUsingContext('ResidentRunner can handle an reload-barred exception from hot reload', () => testbed.run(() async {
@@ -480,7 +477,7 @@ void main() {
         fastReassemble: false,
       )),
     ));
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }, overrides: <Type, Generator>{
     Usage: () => TestUsage(),
   }));
@@ -527,7 +524,7 @@ void main() {
         fastReassemble: false,
       )),
     ));
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }, overrides: <Type, Generator>{
     Usage: () => TestUsage(),
   }));
@@ -546,7 +543,7 @@ void main() {
       ),
       FakeVmServiceRequest(
         method: 'ext.flutter.reassemble',
-        args: <String, Object>{
+        args: <String, Object?>{
           'isolateId': fakeUnpausedIsolate.id,
         },
       ),
@@ -573,7 +570,7 @@ void main() {
     final OperationResult result = await residentRunner.restart();
 
     expect(result.code, 0);
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }));
 
   testUsingContext('ResidentRunner reports error with missing entrypoint file', () => testbed.run(() async {
@@ -587,7 +584,7 @@ void main() {
           'isolates': <Object>[
             fakeUnpausedIsolate.toJson(),
           ],
-        }).toJson(),
+        })!.toJson(),
       ),
       const FakeVmServiceRequest(
         method: 'reloadSources',
@@ -613,7 +610,7 @@ void main() {
       ),
       FakeVmServiceRequest(
         method: 'ext.flutter.reassemble',
-        args: <String, Object>{
+        args: <String, Object?>{
           'isolateId': fakeUnpausedIsolate.id,
         },
       ),
@@ -647,7 +644,7 @@ void main() {
           'isolates': <Object>[
             fakeUnpausedIsolate.toJson(),
           ],
-        }).toJson(),
+        })!.toJson(),
       ),
       const FakeVmServiceRequest(
         method: 'reloadSources',
@@ -677,7 +674,7 @@ void main() {
       ),
       FakeVmServiceRequest(
         method: 'ext.flutter.reassemble',
-        args: <String, Object>{
+        args: <String, Object?>{
           'isolateId': fakeUnpausedIsolate.id,
         },
       ),
@@ -711,7 +708,7 @@ void main() {
           'isolates': <Object>[
             fakeUnpausedIsolate.toJson(),
           ],
-        }).toJson(),
+        })!.toJson(),
       ),
       const FakeVmServiceRequest(
         method: 'reloadSources',
@@ -737,7 +734,7 @@ void main() {
       ),
       FakeVmServiceRequest(
         method: 'ext.flutter.reassemble',
-        args: <String, Object>{
+        args: <String, Object?>{
           'isolateId': fakeUnpausedIsolate.id,
         },
       ),
@@ -758,7 +755,7 @@ void main() {
     final TestUsageEvent event = (globals.flutterUsage as TestUsage).events.first;
     expect(event.category, 'hot');
     expect(event.parameter, 'reload');
-    expect(event.parameters.hotEventTargetPlatform, getNameForTargetPlatform(TargetPlatform.android_arm));
+    expect(event.parameters?.hotEventTargetPlatform, getNameForTargetPlatform(TargetPlatform.android_arm));
   }, overrides: <Type, Generator>{
     Usage: () => TestUsage(),
   }));
@@ -800,7 +797,7 @@ void main() {
       ),
       FakeVmServiceRequest(
         method: 'ext.flutter.fastReassemble',
-        args: <String, Object>{
+        args: <String, Object?>{
           'isolateId': fakeUnpausedIsolate.id,
           'className': 'FOO',
         },
@@ -811,7 +808,7 @@ void main() {
       BuildInfo.debug,
       FakeResidentCompiler(),
       devFS,
-    )..vmService = fakeVmServiceHost.vmService;
+    )..vmService = fakeVmServiceHost!.vmService;
     residentRunner = HotRunner(
       <FlutterDevice>[
         flutterDevice,
@@ -844,7 +841,7 @@ void main() {
     final TestUsageEvent event = (globals.flutterUsage as TestUsage).events.first;
     expect(event.category, 'hot');
     expect(event.parameter, 'reload');
-    expect(event.parameters.fastReassemble, true);
+    expect(event.parameters?.fastReassemble, true);
   }, overrides: <Type, Generator>{
     FileSystem: () => MemoryFileSystem.test(),
     Platform: () => FakePlatform(),
@@ -891,7 +888,7 @@ void main() {
       ),
       FakeVmServiceRequest(
         method: 'ext.flutter.fastReassemble',
-        args: <String, Object>{
+        args: <String, Object?>{
           'isolateId': fakeUnpausedIsolate.id,
           'className': 'FOO',
         },
@@ -902,7 +899,7 @@ void main() {
       BuildInfo.debug,
       FakeResidentCompiler(),
       devFS,
-    )..vmService = fakeVmServiceHost.vmService;
+    )..vmService = fakeVmServiceHost!.vmService;
     residentRunner = HotRunner(
       <FlutterDevice>[
         flutterDevice,
@@ -949,14 +946,14 @@ void main() {
       listViews,
       FakeVmServiceRequest(
         method: 'getIsolate',
-        args: <String, Object>{
+        args: <String, Object?>{
           'isolateId': fakeUnpausedIsolate.id,
         },
         jsonResponse: fakeUnpausedIsolate.toJson(),
       ),
       FakeVmServiceRequest(
         method: 'getVM',
-        jsonResponse: vm_service.VM.parse(<String, Object>{}).toJson(),
+        jsonResponse: vm_service.VM.parse(<String, Object>{})!.toJson(),
       ),
       listViews,
       const FakeVmServiceRequest(
@@ -996,8 +993,8 @@ void main() {
     final TestUsageEvent event = (globals.flutterUsage as TestUsage).events.first;
     expect(event.category, 'hot');
     expect(event.parameter, 'restart');
-    expect(event.parameters.hotEventTargetPlatform, getNameForTargetPlatform(TargetPlatform.android_arm));
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(event.parameters?.hotEventTargetPlatform, getNameForTargetPlatform(TargetPlatform.android_arm));
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }, overrides: <Type, Generator>{
     Usage: () => TestUsage(),
   }));
@@ -1009,14 +1006,14 @@ void main() {
       listViews,
       FakeVmServiceRequest(
         method: 'getIsolate',
-        args: <String, Object>{
+        args: <String, Object?>{
           'isolateId': fakeUnpausedIsolate.id,
         },
         jsonResponse: fakePausedIsolate.toJson(),
       ),
       FakeVmServiceRequest(
         method: 'getVM',
-        jsonResponse: vm_service.VM.parse(<String, Object>{}).toJson(),
+        jsonResponse: vm_service.VM.parse(<String, Object>{})!.toJson(),
       ),
       const FakeVmServiceRequest(
         method: 'setIsolatePauseMode',
@@ -1072,7 +1069,7 @@ void main() {
     final OperationResult result = await residentRunner.restart(fullRestart: true);
 
     expect(result.isOk, true);
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }));
 
   testUsingContext('ResidentRunner will alternative the name of the dill file uploaded for a hot restart', () => testbed.run(() async {
@@ -1082,14 +1079,14 @@ void main() {
       listViews,
       FakeVmServiceRequest(
         method: 'getIsolate',
-        args: <String, Object>{
+        args: <String, Object?>{
           'isolateId': fakeUnpausedIsolate.id,
         },
         jsonResponse: fakeUnpausedIsolate.toJson(),
       ),
       FakeVmServiceRequest(
         method: 'getVM',
-        jsonResponse: vm_service.VM.parse(<String, Object>{}).toJson(),
+        jsonResponse: vm_service.VM.parse(<String, Object>{})!.toJson(),
       ),
       listViews,
       const FakeVmServiceRequest(
@@ -1116,14 +1113,14 @@ void main() {
       listViews,
       FakeVmServiceRequest(
         method: 'getIsolate',
-        args: <String, Object>{
+        args: <String, Object?>{
           'isolateId': fakeUnpausedIsolate.id,
         },
         jsonResponse: fakeUnpausedIsolate.toJson(),
       ),
       FakeVmServiceRequest(
         method: 'getVM',
-        jsonResponse: vm_service.VM.parse(<String, Object>{}).toJson(),
+        jsonResponse: vm_service.VM.parse(<String, Object>{})!.toJson(),
       ),
       listViews,
       const FakeVmServiceRequest(
@@ -1150,14 +1147,14 @@ void main() {
       listViews,
       FakeVmServiceRequest(
         method: 'getIsolate',
-        args: <String, Object>{
+        args: <String, Object?>{
           'isolateId': fakeUnpausedIsolate.id,
         },
         jsonResponse: fakeUnpausedIsolate.toJson(),
       ),
       FakeVmServiceRequest(
         method: 'getVM',
-        jsonResponse: vm_service.VM.parse(<String, Object>{}).toJson(),
+        jsonResponse: vm_service.VM.parse(<String, Object>{})!.toJson(),
       ),
       listViews,
       const FakeVmServiceRequest(
@@ -1194,7 +1191,7 @@ void main() {
     await residentRunner.restart(fullRestart: true);
     await residentRunner.restart(fullRestart: true);
 
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }));
 
   testUsingContext('ResidentRunner Can handle an RPC exception from hot restart', () => testbed.run(() async {
@@ -1225,7 +1222,7 @@ void main() {
         fastReassemble: false,
       )),
     ));
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }, overrides: <Type, Generator>{
     Usage: () => TestUsage(),
   }));
@@ -1554,7 +1551,7 @@ flutter:
     await residentRunner.writeSkSL();
 
     expect(testLogger.statusText, contains('No data was received'));
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }));
 
   testUsingContext('ResidentRunner can write SkSL data to a unique file with engine revision, platform, and device name', () => testbed.run(() async {
@@ -1582,7 +1579,7 @@ flutter:
       'engineRevision': 'abcdefg',
       'data': <String, Object>{'A': 'B'},
     });
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }, overrides: <Type, Generator>{
     FileSystemUtils: () => FileSystemUtils(
       fileSystem: globals.fs,
@@ -1606,7 +1603,7 @@ flutter:
       devtoolsHandler: createNoOpHandler,
     );
 
-    final Future<int> result = residentRunner.attach();
+    final Future<int?> result = residentRunner.attach();
     expect(await result, 0);
   }));
 
@@ -1625,13 +1622,13 @@ flutter:
     final TestFlutterDevice flutterDevice = TestFlutterDevice(
       device,
     );
-    flutterDevice.vmService = fakeVmServiceHost.vmService;
+    flutterDevice.vmService = fakeVmServiceHost!.vmService;
 
     final Future<void> exitFuture = flutterDevice.exitApps();
 
     await expectLater(exitFuture, completes);
     expect(device.appStopped, true);
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }));
 
   testUsingContext('HotRunner writes vm service file when providing debugging option', () => testbed.run(() async {
@@ -1652,7 +1649,7 @@ flutter:
 
     await residentRunner.run(enableDevTools: true);
 
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
     expect(await globals.fs.file('foo').readAsString(), testUri.toString());
   }));
 
@@ -1856,7 +1853,7 @@ flutter:
     await residentRunner.run(enableDevTools: true);
 
     expect(testLogger.errorText, contains('Failed to write vmservice-out-file at foo'));
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }, overrides: <Type, Generator>{
     FileSystem: () => ThrowingForwardingFileSystem(MemoryFileSystem.test()),
   }));
@@ -1879,13 +1876,13 @@ flutter:
     await residentRunner.run(enableDevTools: true);
 
     expect(await globals.fs.file('foo').readAsString(), testUri.toString());
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(fakeVmServiceHost?.hasRemainingExpectations, false);
   }));
 
   testUsingContext('FlutterDevice uses dartdevc configuration when targeting web', () async {
     fakeVmServiceHost = FakeVmServiceHost(requests: <VmServiceExpectation>[]);
     final FakeDevice device = FakeDevice(targetPlatform: TargetPlatform.web_javascript);
-    final DefaultResidentCompiler residentCompiler = (await FlutterDevice.create(
+    final DefaultResidentCompiler? residentCompiler = (await FlutterDevice.create(
       device,
       buildInfo: const BuildInfo(
         BuildMode.debug,
@@ -1895,16 +1892,16 @@ flutter:
       ),
       target: null,
       platform: FakePlatform(),
-    )).generator as DefaultResidentCompiler;
+    )).generator as DefaultResidentCompiler?;
 
-    expect(residentCompiler.initializeFromDill,
+    expect(residentCompiler!.initializeFromDill,
       globals.fs.path.join(getBuildDirectory(), 'fbbe6a61fb7a1de317d381f8df4814e5.cache.dill'));
     expect(residentCompiler.librariesSpec,
-      globals.fs.file(globals.artifacts.getHostArtifact(HostArtifact.flutterWebLibrariesJson))
+      globals.fs.file(globals.artifacts!.getHostArtifact(HostArtifact.flutterWebLibrariesJson))
         .uri.toString());
     expect(residentCompiler.targetModel, TargetModel.dartdevc);
     expect(residentCompiler.sdkRoot,
-      '${globals.artifacts.getHostArtifact(HostArtifact.flutterWebSdk).path}/');
+      '${globals.artifacts!.getHostArtifact(HostArtifact.flutterWebSdk).path}/');
     expect(residentCompiler.platformDill, 'file:///HostArtifact.webPlatformKernelDill');
   }, overrides: <Type, Generator>{
     Artifacts: () => Artifacts.test(),
@@ -1916,7 +1913,7 @@ flutter:
     fakeVmServiceHost = FakeVmServiceHost(requests: <VmServiceExpectation>[]);
     final FakeDevice device = FakeDevice(targetPlatform: TargetPlatform.web_javascript);
 
-    final DefaultResidentCompiler residentCompiler = (await FlutterDevice.create(
+    final DefaultResidentCompiler? residentCompiler = (await FlutterDevice.create(
       device,
       buildInfo: const BuildInfo(
         BuildMode.debug,
@@ -1926,16 +1923,16 @@ flutter:
       ),
       target: null,
       platform: FakePlatform(),
-    )).generator as DefaultResidentCompiler;
+    )).generator as DefaultResidentCompiler?;
 
-    expect(residentCompiler.initializeFromDill,
+    expect(residentCompiler!.initializeFromDill,
       globals.fs.path.join(getBuildDirectory(), '80b1a4cf4e7b90e1ab5f72022a0bc624.cache.dill'));
     expect(residentCompiler.librariesSpec,
-      globals.fs.file(globals.artifacts.getHostArtifact(HostArtifact.flutterWebLibrariesJson))
+      globals.fs.file(globals.artifacts!.getHostArtifact(HostArtifact.flutterWebLibrariesJson))
         .uri.toString());
     expect(residentCompiler.targetModel, TargetModel.dartdevc);
     expect(residentCompiler.sdkRoot,
-      '${globals.artifacts.getHostArtifact(HostArtifact.flutterWebSdk).path}/');
+      '${globals.artifacts!.getHostArtifact(HostArtifact.flutterWebSdk).path}/');
     expect(residentCompiler.platformDill, 'file:///HostArtifact.webPlatformSoundKernelDill');
   }, overrides: <Type, Generator>{
     Artifacts: () => Artifacts.test(),
@@ -1947,7 +1944,7 @@ flutter:
     fakeVmServiceHost = FakeVmServiceHost(requests: <VmServiceExpectation>[]);
     final FakeDevice device = FakeDevice();
 
-    final DefaultResidentCompiler residentCompiler = (await FlutterDevice.create(
+    final DefaultResidentCompiler? residentCompiler = (await FlutterDevice.create(
       device,
       buildInfo: const BuildInfo(
         BuildMode.debug,
@@ -1955,10 +1952,10 @@ flutter:
         treeShakeIcons: false,
         extraFrontEndOptions: <String>[],
       ),
-      target: null, platform: null,
-    )).generator as DefaultResidentCompiler;
+      target: null, platform: FakePlatform(),
+    )).generator as DefaultResidentCompiler?;
 
-    expect(residentCompiler.extraFrontEndOptions,
+    expect(residentCompiler!.extraFrontEndOptions,
       contains('--flutter-widget-cache'));
   }, overrides: <Type, Generator>{
     Artifacts: () => Artifacts.test(),
@@ -1972,7 +1969,7 @@ flutter:
     final FakeDevice device = FakeDevice();
 
 
-    final DefaultResidentCompiler residentCompiler = (await FlutterDevice.create(
+    final DefaultResidentCompiler? residentCompiler = (await FlutterDevice.create(
       device,
       buildInfo: const BuildInfo(
         BuildMode.debug,
@@ -1980,10 +1977,10 @@ flutter:
         treeShakeIcons: false,
         extraFrontEndOptions: <String>[],
       ),
-      target: null, platform: null,
-    )).generator as DefaultResidentCompiler;
+      target: null, platform: FakePlatform(),
+    )).generator as DefaultResidentCompiler?;
 
-    expect(residentCompiler.extraFrontEndOptions,
+    expect(residentCompiler!.extraFrontEndOptions,
       contains('--enable-experiment=alternative-invalidation-strategy'));
   }, overrides: <Type, Generator>{
     Artifacts: () => Artifacts.test(),
@@ -1995,7 +1992,7 @@ flutter:
     fakeVmServiceHost = FakeVmServiceHost(requests: <VmServiceExpectation>[]);
     final FakeDevice device = FakeDevice();
 
-    final DefaultResidentCompiler residentCompiler = (await FlutterDevice.create(
+    final DefaultResidentCompiler? residentCompiler = (await FlutterDevice.create(
       device,
       buildInfo: const BuildInfo(
         BuildMode.debug,
@@ -2004,10 +2001,10 @@ flutter:
         extraFrontEndOptions: <String>[],
         initializeFromDill: '/foo/bar.dill',
       ),
-      target: null, platform: null,
-    )).generator as DefaultResidentCompiler;
+      target: null, platform: FakePlatform(),
+    )).generator as DefaultResidentCompiler?;
 
-    expect(residentCompiler.initializeFromDill, '/foo/bar.dill');
+    expect(residentCompiler!.initializeFromDill, '/foo/bar.dill');
     expect(residentCompiler.assumeInitializeFromDillUpToDate, false);
   }, overrides: <Type, Generator>{
     Artifacts: () => Artifacts.test(),
@@ -2019,7 +2016,7 @@ flutter:
     fakeVmServiceHost = FakeVmServiceHost(requests: <VmServiceExpectation>[]);
     final FakeDevice device = FakeDevice();
 
-    final DefaultResidentCompiler residentCompiler = (await FlutterDevice.create(
+    final DefaultResidentCompiler? residentCompiler = (await FlutterDevice.create(
       device,
       buildInfo: const BuildInfo(
         BuildMode.debug,
@@ -2028,10 +2025,10 @@ flutter:
         extraFrontEndOptions: <String>[],
         assumeInitializeFromDillUpToDate: true,
       ),
-      target: null, platform: null,
-    )).generator as DefaultResidentCompiler;
+      target: null, platform: FakePlatform(),
+    )).generator as DefaultResidentCompiler?;
 
-    expect(residentCompiler.assumeInitializeFromDillUpToDate, true);
+    expect(residentCompiler!.assumeInitializeFromDillUpToDate, true);
   }, overrides: <Type, Generator>{
     Artifacts: () => Artifacts.test(),
     FileSystem: () => MemoryFileSystem.test(),
@@ -2042,7 +2039,7 @@ flutter:
     fakeVmServiceHost = FakeVmServiceHost(requests: <VmServiceExpectation>[]);
     final FakeDevice device = FakeDevice()
       ..dds = DartDevelopmentService();
-    ddsLauncherCallback = (Uri uri, {bool enableAuthCodes, bool ipv6, Uri serviceUri, List<String> cachedUserTags, dds.UriConverter uriConverter}) {
+    ddsLauncherCallback = (Uri uri, {bool enableAuthCodes = true, bool ipv6 = false, Uri? serviceUri, List<String> cachedUserTags = const <String>[], dds.UriConverter? uriConverter}) {
       expect(uri, Uri(scheme: 'foo', host: 'bar'));
       expect(enableAuthCodes, isTrue);
       expect(ipv6, isFalse);
@@ -2062,7 +2059,7 @@ flutter:
     runZonedGuarded(() {
       flutterDevice.connect(allowExistingDdsInstance: true).then((_) => done.complete());
     }, (Object e, StackTrace st) {
-      expect(e is ToolExit, true);
+      expect(e, isA<ToolExit>());
       expect((e as ToolExit).message,
         contains('Existing VM service clients prevent DDS from taking control.',
       ));
@@ -2075,14 +2072,14 @@ flutter:
     }
   }, overrides: <Type, Generator>{
     VMServiceConnector: () => (Uri httpUri, {
-      ReloadSources reloadSources,
-      Restart restart,
-      CompileExpression compileExpression,
-      GetSkSLMethod getSkSLMethod,
-      PrintStructuredErrorLogMethod printStructuredErrorLogMethod,
-      io.CompressionOptions compression,
-      Device device,
-      Logger logger,
+      ReloadSources? reloadSources,
+      Restart? restart,
+      CompileExpression? compileExpression,
+      GetSkSLMethod? getSkSLMethod,
+      PrintStructuredErrorLogMethod? printStructuredErrorLogMethod,
+      io.CompressionOptions? compression,
+      Device? device,
+      required Logger logger,
     }) async => FakeVmServiceHost(requests: <VmServiceExpectation>[]).vmService,
   }));
 
@@ -2091,7 +2088,7 @@ flutter:
     final FakeDevice device = FakeDevice()
       ..dds = DartDevelopmentService();
     final Completer<void>done = Completer<void>();
-    ddsLauncherCallback = (Uri uri, {bool enableAuthCodes, bool ipv6, Uri serviceUri, List<String> cachedUserTags, dds.UriConverter uriConverter}) async {
+    ddsLauncherCallback = (Uri uri, {bool enableAuthCodes = true, bool ipv6 = false, Uri? serviceUri, List<String> cachedUserTags = const <String>[], dds.UriConverter? uriConverter}) async {
       expect(uri, Uri(scheme: 'foo', host: 'bar'));
       expect(enableAuthCodes, isFalse);
       expect(ipv6, isTrue);
@@ -2099,7 +2096,7 @@ flutter:
       expect(cachedUserTags, isEmpty);
       expect(uriConverter, isNull);
       done.complete();
-      return null;
+      return FakeDartDevelopmentService();
     };
     final TestFlutterDevice flutterDevice = TestFlutterDevice(
       device,
@@ -2109,14 +2106,14 @@ flutter:
     await done.future;
   }, overrides: <Type, Generator>{
     VMServiceConnector: () => (Uri httpUri, {
-      ReloadSources reloadSources,
-      Restart restart,
-      CompileExpression compileExpression,
-      GetSkSLMethod getSkSLMethod,
-      PrintStructuredErrorLogMethod printStructuredErrorLogMethod,
-      io.CompressionOptions compression,
-      Device device,
-      Logger logger,
+      ReloadSources? reloadSources,
+      Restart? restart,
+      CompileExpression? compileExpression,
+      GetSkSLMethod? getSkSLMethod,
+      PrintStructuredErrorLogMethod? printStructuredErrorLogMethod,
+      io.CompressionOptions? compression,
+      Device? device,
+      required Logger logger,
     }) async => FakeVmServiceHost(requests: <VmServiceExpectation>[]).vmService,
   }));
 
@@ -2125,7 +2122,14 @@ flutter:
     final FakeDevice device = FakeDevice()
       ..dds = DartDevelopmentService();
     final Completer<void>done = Completer<void>();
-    ddsLauncherCallback = (Uri uri, {bool enableAuthCodes, bool ipv6, Uri serviceUri, List<String> cachedUserTags, dds.UriConverter uriConverter}) async {
+    ddsLauncherCallback = (
+      Uri uri, {
+      bool enableAuthCodes = false,
+      bool ipv6 = false,
+      Uri? serviceUri,
+      List<String> cachedUserTags = const <String>[],
+      dds.UriConverter? uriConverter,
+    }) async {
       expect(uri, Uri(scheme: 'foo', host: 'bar'));
       expect(enableAuthCodes, isFalse);
       expect(ipv6, isTrue);
@@ -2133,7 +2137,7 @@ flutter:
       expect(cachedUserTags, isEmpty);
       expect(uriConverter, isNotNull);
       done.complete();
-      return null;
+      return FakeDartDevelopmentService();
     };
     final TestFlutterDevice flutterDevice = TestFlutterDevice(
       device,
@@ -2143,14 +2147,14 @@ flutter:
     await done.future;
   }, overrides: <Type, Generator>{
     VMServiceConnector: () => (Uri httpUri, {
-      ReloadSources reloadSources,
-      Restart restart,
-      CompileExpression compileExpression,
-      GetSkSLMethod getSkSLMethod,
-      PrintStructuredErrorLogMethod printStructuredErrorLogMethod,
-      io.CompressionOptions compression,
-      Device device,
-      Logger logger,
+      ReloadSources? reloadSources,
+      Restart? restart,
+      CompileExpression? compileExpression,
+      GetSkSLMethod? getSkSLMethod,
+      PrintStructuredErrorLogMethod? printStructuredErrorLogMethod,
+      io.CompressionOptions compression = io.CompressionOptions.compressionDefault,
+      Device? device,
+      required Logger logger,
     }) async => FakeVmServiceHost(requests: <VmServiceExpectation>[]).vmService,
     dds.UriConverter: () => (String uri) => 'test',
   }));
@@ -2159,7 +2163,14 @@ flutter:
     // See https://github.com/flutter/flutter/issues/72385 for context.
     final FakeDevice device = FakeDevice()
       ..dds = DartDevelopmentService();
-    ddsLauncherCallback = (Uri uri, {bool enableAuthCodes, bool ipv6, Uri serviceUri, List<String> cachedUserTags, dds.UriConverter uriConverter}) {
+    ddsLauncherCallback = (
+      Uri uri, {
+      bool enableAuthCodes = false,
+      bool ipv6 = false,
+      Uri? serviceUri,
+      List<String> cachedUserTags = const <String>[],
+      dds.UriConverter? uriConverter,
+    }) {
       expect(uri, Uri(scheme: 'foo', host: 'bar'));
       expect(enableAuthCodes, isTrue);
       expect(ipv6, isFalse);
@@ -2177,7 +2188,7 @@ flutter:
     runZonedGuarded(() {
       flutterDevice.connect(allowExistingDdsInstance: true).then((_) => done.complete());
     }, (Object e, StackTrace st) {
-      expect(e is StateError, true);
+      expect(e, isA<StateError>());
       expect((e as StateError).message, contains('No URI'));
       expect(testLogger.errorText, contains(
         'DDS has failed to start and there is not an existing DDS instance',
@@ -2191,14 +2202,14 @@ flutter:
     }
   }, overrides: <Type, Generator>{
     VMServiceConnector: () => (Uri httpUri, {
-      ReloadSources reloadSources,
-      Restart restart,
-      CompileExpression compileExpression,
-      GetSkSLMethod getSkSLMethod,
-      PrintStructuredErrorLogMethod printStructuredErrorLogMethod,
-      io.CompressionOptions compression,
-      Device device,
-      Logger logger,
+      ReloadSources? reloadSources,
+      Restart? restart,
+      CompileExpression? compileExpression,
+      GetSkSLMethod? getSkSLMethod,
+      PrintStructuredErrorLogMethod? printStructuredErrorLogMethod,
+      io.CompressionOptions compression = io.CompressionOptions.compressionDefault,
+      Device? device,
+      required Logger logger,
     }) async => FakeVmServiceHost(requests: <VmServiceExpectation>[]).vmService,
   }));
 
@@ -2222,7 +2233,7 @@ flutter:
     );
     await residentRunner.cleanupAtFinish();
 
-    expect((residentRunner.residentDevtoolsHandler as NoOpDevtoolsHandler).wasShutdown, true);
+    expect((residentRunner.residentDevtoolsHandler! as NoOpDevtoolsHandler).wasShutdown, true);
   }));
 
   testUsingContext('HotRunner sets asset directory when first evict assets', () => testbed.run(() async {
@@ -2241,12 +2252,12 @@ flutter:
       devtoolsHandler: createNoOpHandler,
     );
 
-    (flutterDevice.devFS as FakeDevFS).assetPathsToEvict = <String>{'asset'};
+    (flutterDevice.devFS! as FakeDevFS).assetPathsToEvict = <String>{'asset'};
 
-    expect(flutterDevice.devFS.hasSetAssetDirectory, false);
+    expect(flutterDevice.devFS!.hasSetAssetDirectory, isFalse);
     await (residentRunner as HotRunner).evictDirtyAssets();
-    expect(flutterDevice.devFS.hasSetAssetDirectory, true);
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(flutterDevice.devFS!.hasSetAssetDirectory, isTrue);
+    expect(fakeVmServiceHost!.hasRemainingExpectations, isFalse);
   }));
 
   testUsingContext('HotRunner sets asset directory when first evict shaders', () => testbed.run(() async {
@@ -2265,12 +2276,12 @@ flutter:
       devtoolsHandler: createNoOpHandler,
     );
 
-    (flutterDevice.devFS as FakeDevFS).shaderPathsToEvict = <String>{'foo.frag'};
+    (flutterDevice.devFS! as FakeDevFS).shaderPathsToEvict = <String>{'foo.frag'};
 
-    expect(flutterDevice.devFS.hasSetAssetDirectory, false);
+    expect(flutterDevice.devFS!.hasSetAssetDirectory, false);
     await (residentRunner as HotRunner).evictDirtyAssets();
-    expect(flutterDevice.devFS.hasSetAssetDirectory, true);
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(flutterDevice.devFS!.hasSetAssetDirectory, true);
+    expect(fakeVmServiceHost!.hasRemainingExpectations, false);
   }));
 
   testUsingContext('HotRunner does not sets asset directory when no assets to evict', () => testbed.run(() async {
@@ -2286,10 +2297,10 @@ flutter:
       devtoolsHandler: createNoOpHandler,
     );
 
-    expect(flutterDevice.devFS.hasSetAssetDirectory, false);
+    expect(flutterDevice.devFS!.hasSetAssetDirectory, false);
     await (residentRunner as HotRunner).evictDirtyAssets();
-    expect(flutterDevice.devFS.hasSetAssetDirectory, false);
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(flutterDevice.devFS!.hasSetAssetDirectory, false);
+    expect(fakeVmServiceHost!.hasRemainingExpectations, false);
   }));
 
   testUsingContext('HotRunner does not set asset directory if it has been set before', () => testbed.run(() async {
@@ -2307,15 +2318,25 @@ flutter:
       devtoolsHandler: createNoOpHandler,
     );
 
-    (flutterDevice.devFS as FakeDevFS).assetPathsToEvict = <String>{'asset'};
-    flutterDevice.devFS.hasSetAssetDirectory = true;
+    (flutterDevice.devFS! as FakeDevFS).assetPathsToEvict = <String>{'asset'};
+    flutterDevice.devFS!.hasSetAssetDirectory = true;
 
     await (residentRunner as HotRunner).evictDirtyAssets();
-    expect(flutterDevice.devFS.hasSetAssetDirectory, true);
-    expect(fakeVmServiceHost.hasRemainingExpectations, false);
+    expect(flutterDevice.devFS!.hasSetAssetDirectory, true);
+    expect(fakeVmServiceHost!.hasRemainingExpectations, false);
   }));
 }
 
+// NOTE: implements [dds.DartDevelopmentService] and NOT [DartDevelopmentService]
+// from package:flutter_tools.
+class FakeDartDevelopmentService extends Fake implements dds.DartDevelopmentService {
+  @override
+  Future<void> get done => Future<void>.value();
+
+  @override
+  Uri? get uri => null;
+}
+
 class FakeDartDevelopmentServiceException implements dds.DartDevelopmentServiceException {
   FakeDartDevelopmentServiceException({this.message = defaultMessage});
 
@@ -2328,18 +2349,17 @@ class FakeDartDevelopmentServiceException implements dds.DartDevelopmentServiceE
 }
 
 class TestFlutterDevice extends FlutterDevice {
-  TestFlutterDevice(Device device, { Stream<Uri> observatoryUris })
-    : super(device, buildInfo: BuildInfo.debug, developmentShaderCompiler: const FakeShaderCompiler()) {
-    _observatoryUris = observatoryUris;
-  }
+  TestFlutterDevice(super.device, { Stream<Uri>? observatoryUris })
+    : _observatoryUris = observatoryUris, super(buildInfo: BuildInfo.debug, developmentShaderCompiler: const FakeShaderCompiler());
+
+  final Stream<Uri>? _observatoryUris;
 
   @override
-  Stream<Uri> get observatoryUris => _observatoryUris;
-  Stream<Uri> _observatoryUris;
+  Stream<Uri> get observatoryUris => _observatoryUris!;
 }
 
 class ThrowingForwardingFileSystem extends ForwardingFileSystem {
-  ThrowingForwardingFileSystem(FileSystem delegate) : super(delegate);
+  ThrowingForwardingFileSystem(super.delegate);
 
   @override
   File file(dynamic path) {
@@ -2351,19 +2371,19 @@ class ThrowingForwardingFileSystem extends ForwardingFileSystem {
 }
 
 class FakeFlutterDevice extends Fake implements FlutterDevice {
-  FakeVmServiceHost Function() vmServiceHost;
-  Uri testUri;
+  FakeVmServiceHost? Function()? vmServiceHost;
+  Uri? testUri;
   UpdateFSReport report = UpdateFSReport(
     success: true,
     invalidatedSourcesCount: 1,
   );
-  Exception reportError;
-  Exception runColdError;
+  Exception? reportError;
+  Exception? runColdError;
   int runHotCode = 0;
   int runColdCode = 0;
 
   @override
-  ResidentCompiler generator;
+  ResidentCompiler? generator;
 
   @override
   DevelopmentShaderCompiler get developmentShaderCompiler => const FakeShaderCompiler();
@@ -2372,21 +2392,21 @@ class FakeFlutterDevice extends Fake implements FlutterDevice {
   TargetPlatform get targetPlatform => TargetPlatform.android;
 
   @override
-  Stream<Uri> get observatoryUris => Stream<Uri>.value(testUri);
+  Stream<Uri?> get observatoryUris => Stream<Uri?>.value(testUri);
 
   @override
-  FlutterVmService get vmService => vmServiceHost?.call()?.vmService;
+  FlutterVmService? get vmService => vmServiceHost?.call()?.vmService;
 
-  DevFS _devFS;
+  DevFS? _devFS;
 
   @override
-  DevFS get devFS => _devFS;
+  DevFS? get devFS => _devFS;
 
   @override
-  set devFS(DevFS value) { }
+  set devFS(DevFS? value) { }
 
   @override
-  Device device;
+  Device? device;
 
   @override
   Future<void> stopEchoingDeviceLog() async { }
@@ -2396,55 +2416,55 @@ class FakeFlutterDevice extends Fake implements FlutterDevice {
 
   @override
   Future<Uri> setupDevFS(String fsName, Directory rootDirectory) async {
-    return testUri;
+    return testUri!;
   }
 
   @override
-  Future<int> runHot({HotRunner hotRunner, String route}) async {
+  Future<int> runHot({required HotRunner hotRunner, String? route}) async {
     return runHotCode;
   }
 
   @override
-  Future<int> runCold({ColdRunner coldRunner, String route}) async {
+  Future<int> runCold({required ColdRunner coldRunner, String? route}) async {
     if (runColdError != null) {
-      throw runColdError;
+      throw runColdError!;
     }
     return runColdCode;
   }
 
   @override
   Future<void> connect({
-    ReloadSources reloadSources,
-    Restart restart,
-    CompileExpression compileExpression,
-    GetSkSLMethod getSkSLMethod,
-    PrintStructuredErrorLogMethod printStructuredErrorLogMethod,
-    int hostVmServicePort,
-    int ddsPort,
+    ReloadSources? reloadSources,
+    Restart? restart,
+    CompileExpression? compileExpression,
+    GetSkSLMethod? getSkSLMethod,
+    PrintStructuredErrorLogMethod? printStructuredErrorLogMethod,
+    int? hostVmServicePort,
+    int? ddsPort,
     bool disableServiceAuthCodes = false,
     bool enableDds = true,
     bool cacheStartupProfile = false,
-    @required bool allowExistingDdsInstance,
+    required bool allowExistingDdsInstance,
     bool ipv6 = false,
   }) async { }
 
   @override
   Future<UpdateFSReport> updateDevFS({
-    Uri mainUri,
-    String target,
-    AssetBundle bundle,
-    DateTime firstBuildTime,
+    required Uri mainUri,
+    String? target,
+    AssetBundle? bundle,
+    DateTime? firstBuildTime,
     bool bundleFirstUpload = false,
     bool bundleDirty = false,
     bool fullRestart = false,
-    String projectRootPath,
-    String pathToReload,
-    String dillOutputPath,
-    List<Uri> invalidatedFiles,
-    PackageConfig packageConfig,
+    String? projectRootPath,
+    required String pathToReload,
+    required String dillOutputPath,
+    required List<Uri> invalidatedFiles,
+    required PackageConfig packageConfig,
   }) async {
     if (reportError != null) {
-      throw reportError;
+      throw reportError!;
     }
     return report;
   }
@@ -2455,25 +2475,25 @@ class FakeFlutterDevice extends Fake implements FlutterDevice {
 
 class FakeDelegateFlutterDevice extends FlutterDevice {
   FakeDelegateFlutterDevice(
-    Device device,
+    super.device,
     BuildInfo buildInfo,
     ResidentCompiler residentCompiler,
     this.fakeDevFS,
-  ) : super(device, buildInfo: buildInfo, generator: residentCompiler, developmentShaderCompiler: const FakeShaderCompiler());
+  ) : super(buildInfo: buildInfo, generator: residentCompiler, developmentShaderCompiler: const FakeShaderCompiler());
 
   @override
   Future<void> connect({
-    ReloadSources reloadSources,
-    Restart restart,
+    ReloadSources? reloadSources,
+    Restart? restart,
     bool enableDds = true,
     bool cacheStartupProfile = false,
     bool disableServiceAuthCodes = false,
     bool ipv6 = false,
-    CompileExpression compileExpression,
-    GetSkSLMethod getSkSLMethod,
-    int hostVmServicePort,
-    int ddsPort,
-    PrintStructuredErrorLogMethod printStructuredErrorLogMethod,
+    CompileExpression? compileExpression,
+    GetSkSLMethod? getSkSLMethod,
+    int? hostVmServicePort,
+    int? ddsPort,
+    PrintStructuredErrorLogMethod? printStructuredErrorLogMethod,
     bool allowExistingDdsInstance = false,
   }) async { }
 
@@ -2481,27 +2501,27 @@ class FakeDelegateFlutterDevice extends FlutterDevice {
   final DevFS fakeDevFS;
 
   @override
-  DevFS get devFS => fakeDevFS;
+  DevFS? get devFS => fakeDevFS;
 
   @override
-  set devFS(DevFS value) {}
+  set devFS(DevFS? value) {}
 }
 
 class FakeResidentCompiler extends Fake implements ResidentCompiler {
-  CompilerOutput nextOutput;
+  CompilerOutput? nextOutput;
   bool didSuppressErrors = false;
 
   @override
-  Future<CompilerOutput> recompile(
+  Future<CompilerOutput?> recompile(
     Uri mainUri,
-    List<Uri> invalidatedFiles, {
-    @required String outputPath,
-    @required PackageConfig packageConfig,
-    @required String projectRootPath,
-    @required FileSystem fs,
+    List<Uri>? invalidatedFiles, {
+    required String outputPath,
+    required PackageConfig packageConfig,
+    String? projectRootPath,
+    required FileSystem fs,
     bool suppressErrors = false,
     bool checkDartPluginRegistry = false,
-    File dartPluginRegistrant,
+    File? dartPluginRegistrant,
   }) async {
     didSuppressErrors = suppressErrors;
     return nextOutput ?? const CompilerOutput('foo.dill', 0, <Uri>[]);
@@ -2517,14 +2537,14 @@ class FakeResidentCompiler extends Fake implements ResidentCompiler {
 class FakeProjectFileInvalidator extends Fake implements ProjectFileInvalidator {
   @override
   Future<InvalidationResult> findInvalidated({
-    @required DateTime lastCompiled,
-    @required List<Uri> urisToMonitor,
-    @required String packagesPath,
-    @required PackageConfig packageConfig,
+    required DateTime? lastCompiled,
+    required List<Uri> urisToMonitor,
+    required String packagesPath,
+    required PackageConfig packageConfig,
     bool asyncScanning = false,
   }) async {
     return InvalidationResult(
-      packageConfig: packageConfig ?? PackageConfig.empty,
+      packageConfig: packageConfig,
       uris: <Uri>[Uri.parse('file:///hello_world/main.dart'),
     ]);
   }
@@ -2580,7 +2600,7 @@ class FakeDevice extends Fake implements Device {
   String get name => 'FakeDevice';
 
   @override
-  DartDevelopmentService dds;
+  late DartDevelopmentService dds;
 
   @override
   Future<void> dispose() async {
@@ -2588,7 +2608,7 @@ class FakeDevice extends Fake implements Device {
   }
 
   @override
-  Future<bool> stopApp(covariant ApplicationPackage app, {String userIdentifier}) async {
+  Future<bool> stopApp(covariant ApplicationPackage? app, {String? userIdentifier}) async {
     appStopped = true;
     return true;
   }
@@ -2603,7 +2623,7 @@ class FakeDevice extends Fake implements Device {
 
   @override
   FutureOr<DeviceLogReader> getLogReader({
-    covariant ApplicationPackage app,
+    covariant ApplicationPackage? app,
     bool includePastLogs = false,
   }) => NoOpDeviceLogReader(name);
 
@@ -2613,10 +2633,10 @@ class FakeDevice extends Fake implements Device {
 
 class FakeDevFS extends Fake implements DevFS {
   @override
-  DateTime lastCompiled = DateTime(2000);
+  DateTime? lastCompiled = DateTime(2000);
 
   @override
-  PackageConfig lastPackageConfig = PackageConfig.empty;
+  PackageConfig? lastPackageConfig = PackageConfig.empty;
 
   @override
   List<Uri> sources = <Uri>[];
@@ -2653,22 +2673,22 @@ class FakeDevFS extends Fake implements DevFS {
 
   @override
   Future<UpdateFSReport> update({
-    @required Uri mainUri,
-    @required ResidentCompiler generator,
-    @required bool trackWidgetCreation,
-    @required String pathToReload,
-    @required List<Uri> invalidatedFiles,
-    @required PackageConfig packageConfig,
-    @required String dillOutputPath,
-    @required DevelopmentShaderCompiler shaderCompiler,
-    DevFSWriter devFSWriter,
-    String target,
-    AssetBundle bundle,
-    DateTime firstBuildTime,
+    required Uri mainUri,
+    required ResidentCompiler generator,
+    required bool trackWidgetCreation,
+    required String pathToReload,
+    required List<Uri> invalidatedFiles,
+    required PackageConfig packageConfig,
+    required String dillOutputPath,
+    required DevelopmentShaderCompiler shaderCompiler,
+    DevFSWriter? devFSWriter,
+    String? target,
+    AssetBundle? bundle,
+    DateTime? firstBuildTime,
     bool bundleFirstUpload = false,
     bool fullRestart = false,
-    String projectRootPath,
-    File dartPluginRegistrant,
+    String? projectRootPath,
+    File? dartPluginRegistrant,
   }) async {
     return nextUpdateReport;
   }
@@ -2678,7 +2698,7 @@ class FakeShaderCompiler implements DevelopmentShaderCompiler {
   const FakeShaderCompiler();
 
   @override
-  void configureCompiler(TargetPlatform platform, { @required bool enableImpeller }) { }
+  void configureCompiler(TargetPlatform? platform, { required bool enableImpeller }) { }
 
   @override
   Future<DevFSContent> recompileShader(DevFSContent inputShader) {