'！navigator._debugLocked'：在导航到新屏幕时不正确

Question

我正在尝试从AWS Amplify获得响应，当结果成功时，我需要将用户重定向到另一个屏幕。当我运行代码时，它会给我

E/flutter ( 4656): [ERROR:flutter/lib/ui/ui_dart_state.cc(177)] Unhandled Exception: 'package:flutter/src/widgets/navigator.dart': Failed assertion: line 2416 pos 18: '!navigator._debugLocked': is not true.

给予红色危险区域。应该采取什么措施避免出现红色区域并顺利导航到另一个屏幕。

@override
Widget build(BuildContext context) {
 return Scaffold(
   resizeToAvoidBottomInset: true,
   body: StreamBuilder<String>(
     stream: _bloc.postrequestStream,
     builder: (BuildContext context,AsyncSnapshot<String> snapshot){
       if(snapshot.data == null)
        return LoginComponents(snapshot.data);
       else {
         if (snapshot.data == "Failed") {
           print('Arpit: ' + snapshot.data);
           Fluttertoast.showToast(
               msg: "Invalid username or password",
               toastLength: Toast.LENGTH_SHORT,
               gravity: ToastGravity.BOTTOM,
               timeInSecForIosWeb: 1,
               backgroundColor: Colors.red,
               textColor: Colors.white,
               fontSize: 16.0
           );
           return LoginComponents(snapshot.data);
         }
         else {
          Navigator.of(context).pushNamed('/playerdashboard');
           return Container();
         }
      }
     },
   )
 );
}