我是 flutter 新手，我仍在学习基础知识，但我遇到了这个异常：setState() 或 markNeedsBuild() 和异常：失败的断言：第 4134 行 pos 12：'!_debugLocked'：不是真的 //第一个代码是主文件，第二个是抽屉文件，其中任何一个都没有错误

    
void main() => runApp(MyApp());

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  Map<String,bool> _filters = {
    'gluten': false,'lactose': false,'vegan': false,'vegetarian': false,};
  List<Meal> _availableMeals = DUMMY_MEALS;
  List<Meal> _favoriteMeals = [];

  void _setfilters(Map<String,bool> filterData) {
    if (!mounted) return;
    setState(() {
      _filters = filterData;

      _availableMeals = DUMMY_MEALS.where((meal) {
        if (_filters['gluten'] == true && !meal.isGlutenFree) {
          return false;
        }
        if (_filters['lactose'] = true && !meal.isLactoseFree) {
          return false;
        }
        if (_filters['vegan'] == true && !meal.isVegan) {
          return false;
        }
        if (_filters['vegetarian'] == true && !meal.isVegetarian) {
          return false;
        }
        return true;
      }).toList();
    });
  }

  void _toggleFavorite(String mealId) {
    final existingIndex =
        _favoriteMeals.indexWhere((meal) => meal.id == mealId);
    if (existingIndex >= 0) {
      if (!mounted) return;
      setState(() {
        _favoriteMeals.removeAt(existingIndex);
      });
    } else {
      if (!mounted) return;
      setState(() {
        _favoriteMeals.add(
          DUMMY_MEALS.firstWhere((meal) => meal.id == mealId),);
      });
    }
  }

  bool _isMealFavorite(String id) {
    return _favoriteMeals.any((meal) => meal.id == id);
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'DeliMeals',theme: ThemeData(
        primarySwatch: Colors.pink,accentColor: Colors.amber,canvasColor: Color.fromRGBO(255,254,229,1),fontFamily: 'Raleway',textTheme: ThemeData.light().textTheme.copyWith(
            bodyText2: TextStyle(
              color: Color.fromRGBO(20,51,),bodyText1: TextStyle(
              color: Color.fromRGBO(20,headline6: TextStyle(
              fontSize: 20,fontFamily: 'RobotoCondensed',fontWeight: FontWeight.bold,)),// home: CategoriesScreen(),initialRoute: '/',// default is '/'
      routes: {
        '/': (ctx) => TabsScreen(_favoriteMeals),CategoryMealsScreen.routeName: (ctx) =>
            CategoryMealsScreen(_availableMeals),MealDetailScreen.routeName: (ctx) =>
            MealDetailScreen(_toggleFavorite,_isMealFavorite),FiltersScreen.routeName: (ctx) => FiltersScreen(_filters,_setfilters),},onGenerateRoute: (settings) {
        print(settings.arguments);
        // if (settings.name == '/meal-detail') {
        //   return ...;
        // } else if (settings.name == '/something-else') {
        //   return ...;
        // }
        // return MaterialPageRoute(builder: (ctx) => CategoriesScreen(),);
      },onUnknownRoute: (settings) {
        return MaterialPageRoute(
          builder: (ctx) => CategoriesScreen(),);
  }
}  ```


    class MainDrawer extends StatelessWidget {
      
      Widget buildListTile(String title,IconData icon,Function tapHandler) {
        return ListTile(
          leading: Icon(
            icon,size: 26,title: Text(
            title,style: TextStyle(
              fontFamily: 'RobotoCondensed',fontSize: 24,onTap: tapHandler(),);
      }
    
      @override
      Widget build(BuildContext context) {
        return Drawer(
          child: Column(
            children: <Widget>[
              Container(
                height: 120,width: double.infinity,padding: EdgeInsets.all(20),alignment: Alignment.centerLeft,color: Theme.of(context).accentColor,child: Text(
                  'Cooking Up!',style: TextStyle(
                      fontWeight: FontWeight.w900,fontSize: 30,color: Theme.of(context).primaryColor),SizedBox(
                height: 20,buildListTile('Meals',Icons.restaurant,() {
                Navigator.of(context).pushReplacementNamed('/');
              }),buildListTile('Filters',Icons.settings,() {
                Navigator.of(context).pushReplacementNamed(FiltersScreen.routeName);
              }),],);
      }
    }

Error:

    exception:Failed assertion: line 4134 pos 12: '!_debugLocked': is not true