错误:在此BlocBuilder<NavBloc上找不到正确的Provider<NavBloc>，NavState>小部件

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

class NavBloc extends Bloc<NavEvent, NavState> {
  // 实现NavBloc的逻辑
}

class NavState {
  // 实现NavState的状态
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: BlocProvider<NavBloc>(
        create: (context) => NavBloc(),
        child: MyHomePage(),
      ),
    );
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('My App'),
      ),
      body: BlocBuilder<NavBloc, NavState>(
        builder: (context, state) {
          // 根据NavState构建UI
          return Container();
        },
      ),
    );
  }
}

void main() {
  runApp(MyApp());
}