在初始化BLoC时，我应该如何处理异步调用？

class MyBloc {
  final _repository = MyRepository();

  Future<MyData> fetchData() async {
    return await _repository.fetchData();
  }
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('My App')),
      body: FutureBuilder<MyData>(
        future: MyBloc().fetchData(),
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return Center(child: CircularProgressIndicator());
          } else if (snapshot.hasError) {
            return Center(child: Text('Error: ${snapshot.error}'));
          } else {
            return Center(child: Text('Data: ${snapshot.data}'));
          }
        },
      ),
    );
  }
}

class MyBloc {
  final _repository = MyRepository();
  final _streamController = StreamController<MyData>.broadcast();

  Stream<MyData> get dataStream => _streamController.stream;

  void fetchData() async {
    try {
      final data = await _repository.fetchData();
      _streamController.add(data);
    } catch (e) {
      _streamController.addError(e);
    }
  }

  void dispose() {
    _streamController.close();
  }
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('My App')),
      body: StreamBuilder<MyData>(
        stream: MyBloc().dataStream,
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return Center(child: CircularProgressIndicator());
          } else if (snapshot.hasError) {
            return Center(child: Text('Error: ${snapshot.error}'));
          } else if (snapshot.hasData) {
            return Center(child: Text('Data: ${snapshot.data}'));
          } else {
            return Container();
          }
        },
      ),
    );
  }
}

class MyBloc {
  final _repository = MyRepository();

  Future<MyData> fetchData() async {
    try {
      final data = await _repository.fetchData();
      return data;
    } catch (e) {
      throw e;
    }
  }
}

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  Future<MyData> _dataFuture;

  @override
  void initState() {
    super.initState();
    _dataFuture = MyBloc().fetchData();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('My App')),
      body: FutureBuilder<MyData>(
        future: _dataFuture,
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waitiaing) {
            return Center(child: CircularProgressIndicator());
          } else if (snapshot.hasError) {
            return Center(child: Text('Error: ${snapshot.error}'));
          } else {
            return Center(child: Text('Data: ${snapshot.data}'));
          }
        },
      ),
    );
  }
}