anchor.diff:              'Timed out trying to fetch flutter version from '
               '`ConnectedApp.initializeValues`.',
             );
  -          return Future<FlutterVersion>.value();
  +          return Future<FlutterVersion?>.value();
           },
         );
         flutterVersionServiceListenable.removeListener(listener);
  
positive.code:   Future<bool> get isFlutterApp async => _isFlutterApp ??=
        await serviceManager.libraryUriAvailable(flutterLibraryUri);
  
    bool get isFlutterAppNow {
      assert(_isFlutterApp != null);
      return _isFlutterApp;
    }
  
    bool _isFlutterApp;
  
    FlutterVersion get flutterVersionNow {
      return isFlutterNativeAppNow ? _flutterVersion : null;
    }
  
    FlutterVersion _flutterVersion;
  
    final _flutterVersionCompleter = Completer<FlutterVersion>();
  
    static const _flutterVersionTimeout = Duration(seconds: 3);
  
    Future<bool> get isProfileBuild async {
      _isProfileBuild ??= await _connectedToProfileBuild();
      return _isProfileBuild;
    }
  
    bool get isProfileBuildNow {
      assert(_isProfileBuild != null);
      return _isProfileBuild;
    }
  
    bool _isProfileBuild;
  
    // TODO(kenz): investigate if we can use `libraryUriAvailableNow` instead.
    Future<bool> get isDartWebApp async => _isDartWebApp ??=
        await serviceManager.libraryUriAvailable(dartHtmlLibraryUri);
  
    bool get isDartWebAppNow {
      assert(_isDartWebApp != null);
      return _isDartWebApp;
    }
  
    bool _isDartWebApp;
  
    bool get isFlutterWebAppNow => isFlutterAppNow && isDartWebAppNow;
  
    bool get isFlutterNativeAppNow => isFlutterAppNow && !isDartWebAppNow;
  
    bool get isDebugFlutterAppNow => isFlutterAppNow && !isProfileBuildNow;
  
    bool get isRunningOnDartVM => serviceManager.vm.name != 'ChromeDebugProxy';
  
    Future<bool> get isDartCliApp async =>
        isRunningOnDartVM && !(await isFlutterApp);
  
    bool get isDartCliAppNow => isRunningOnDartVM && !isFlutterAppNow;
  
    Future<bool> _connectedToProfileBuild() async {
      // If Dart or Flutter web, assume profile is false.
      if (!isRunningOnDartVM) {
        return false;
      }
  
  
negative.code:       flutterVersionServiceListenable.addListener(listener = () async {
          final registered = flutterVersionServiceListenable.value;
          if (registered) {
            _flutterVersionCompleter.complete(FlutterVersion.parse(
                (await serviceManager.flutterVersion).json!));
          }
        });
  
  