handle an exit code from android n (#3914)

* handle an exit code from android n

* review comments

packages/flutter_tools/lib/src/android/android_device.dart

@@ -54,13 +54,19 @@ class AndroidDevice extends Device {
 
   String _getProperty(String name) {
     if (_properties == null) {
+      _properties = <String, String>{};
+
+      try {
         String getpropOutput = runCheckedSync(adbCommandForDevice(<String>['shell', 'getprop']));
         RegExp propertyExp = new RegExp(r'\[(.*?)\]: \[(.*?)\]');
-      _properties = <String, String>{};
-      for (Match m in propertyExp.allMatches(getpropOutput)) {
+        for (Match m in propertyExp.allMatches(getpropOutput))
           _properties[m.group(1)] = m.group(2);
+      } catch (error, trace) {
+        printError('Error retrieving device properties: $error');
+        printTrace(trace.toString());
       }
     }
+
     return _properties[name];
   }
 

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

@@ -6,6 +6,8 @@ import 'dart:async';
 
 final AppContext _defaultContext = new AppContext();
 
+typedef void ErrorHandler(dynamic error);
+
 /// A singleton for application functionality. This singleton can be different
 /// on a per-Zone basis.
 AppContext get context {
@@ -56,7 +58,11 @@ class AppContext {
     }
   }
 
-  dynamic runInZone(dynamic method()) {
-    return runZoned(method, zoneValues: <String, dynamic>{'context': this});
+  dynamic runInZone(dynamic method(), { ErrorHandler onError }) {
+    return runZoned(
+      method,
+      zoneValues: <String, dynamic>{ 'context': this },
+      onError: onError
+    );
   }
 }

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

@@ -64,7 +64,7 @@ class DaemonCommand extends FlutterCommand {
       }, daemonCommand: this, notifyingLogger: notifyingLogger);
 
       return daemon.onExit;
-    });
+    }, onError: _handleError);
   }
 
   dynamic _jsonEncodeObject(dynamic object) {
@@ -72,6 +72,10 @@ class DaemonCommand extends FlutterCommand {
       return _deviceToMap(object);
     return object;
   }
+
+  void _handleError(dynamic error) {
+    printError('Error from flutter daemon: $error');
+  }
 }
 
 typedef void DispatchComand(Map<String, dynamic> command);