Remove unnecessary null checks in ‘dev/conductor’ (#118843)

* Remove unnecessary null checks in dev/conductor

* review

dev/conductor/core/lib/src/globals.dart

@@ -126,7 +126,7 @@ List<String> getValuesFromEnvOrArgs(
   if (env[envName] != null && env[envName] != '') {
     return env[envName]!.split(',');
   }
-  final List<String> argValues = argResults[name] as List<String>;
+  final List<String>? argValues = argResults[name] as List<String>?;
   if (argValues != null) {
     return argValues;
   }

dev/conductor/core/lib/src/repository.dart

@@ -28,7 +28,6 @@ class Remote {
     required RemoteName name,
     required this.url,
   })  : _name = name,
-        assert(url != null),
         assert(url != '');
 
   factory Remote.mirror(String url) {
@@ -241,7 +240,6 @@ abstract class Repository {
 
   /// The URL of the remote named [remoteName].
   Future<String> remoteUrl(String remoteName) async {
-    assert(remoteName != null);
     return git.getOutput(
       <String>['remote', 'get-url', remoteName],
       'verify the URL of the $remoteName remote',

dev/conductor/core/lib/src/state.dart

@@ -86,8 +86,7 @@ String presentState(pb.ConductorState state) {
   } else {
     buffer.writeln('0 Engine cherrypicks.');
   }
-  if (state.engine.dartRevision != null &&
-      state.engine.dartRevision.isNotEmpty) {
+  if (state.engine.dartRevision.isNotEmpty) {
     buffer.writeln('New Dart SDK revision: ${state.engine.dartRevision}');
   }
   buffer.writeln('Framework Repo');
@@ -271,7 +270,6 @@ String githubAccount(String remoteUrl) {
 /// Will throw a [ConductorException] if [ReleasePhase.RELEASE_COMPLETED] is
 /// passed as an argument, as there is no next phase.
 ReleasePhase getNextPhase(ReleasePhase currentPhase) {
-  assert(currentPhase != null);
   final ReleasePhase? nextPhase = ReleasePhase.valueOf(currentPhase.value + 1);
   if (nextPhase == null) {
     throw globals.ConductorException('There is no next ReleasePhase!');

dev/conductor/core/lib/src/version.dart

@@ -77,7 +77,6 @@ class Version {
   /// `flutter --version` and match one of `stablePattern`, `developmentPattern`
   /// and `latestPattern`.
   factory Version.fromString(String versionString) {
-    assert(versionString != null);
 
     versionString = versionString.trim();
     // stable tag