重新进入子页面时出现颤振错误

Question

我正在使用 Sockets 编写简单的聊天应用程序。当我将主页更改为子页面时，它工作正常，但是当我返回主屏幕并再次进入子页面时，它会显示如下错误：[ERROR:flutter/lib/ui/ui_dart_state.cc(213)] Unhandled Exception: Cannot hit test a render box that has never been laid out. The hitTest() method was called on this RenderBox: RenderErrorBox#b3570 NEEDS-LAYOUT NEEDS-PAINT: creator: ErrorWidget-[#74fe9] ← _BodyBuilder ← MediaQuery ← LayoutId-[<_ScaffoldSlot.body>] ← CustomMultiChildLayout ← AnimatedBuilder ← DefaultTextStyle ← AnimatedDefaultTextStyle ← _InkFeatures-[GlobalKey#ccc61 ink renderer] ← NotificationListener<LayoutChangedNotification> ← PhysicalModel ← AnimatedPhysicalModel ← ⋯ parentData: offset=Offset(0.0, 0.0); id=_ScaffoldSlot.body constraints: MISSING size: MISSING Unfortunately, this object's geometry is not known at this time, probably because it has never been laid out. This means it cannot be accurately hit-tested. If you are trying to perform a hit test during the layout phase itself, make sure you only hit test nodes that have completed layout (e.g. the node's children, after their layout() method has been called). #0 RenderBox.hitTest.<anonymous closure> (package:flutter/src/rendering/box.dart:2380:11)

我不确定它来自哪里。也许它与 Socket 连接有某种连接，我将其作为参数传递给 subPage 的构造函数。我感谢所有帮助，提前致谢！ 子页面代码：

import 'dart:typed_data';

import 'package:chat_app/models/ChatUsers.dart';
import 'package:flutter/material.dart';
import 'dart:io';
import 'package:chat_app/globals.dart' as globals;

// Define a custom Form widget.
class RegisterScreen extends StatefulWidget {
  late final Socket channel;
  RegisterScreen(Socket s) {
    this.channel = s;
  }

  @override
  _RegisterScreenState createState() => _RegisterScreenState();
}

class _RegisterScreenState extends State<RegisterScreen> {
  List<int> lint = [];
  int i=0;
  late ChatUsers user;
  final TextEditingController _controller = TextEditingController();

  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("widget.title"),
      ),
      body: Padding(
        padding: const EdgeInsets.all(20.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            Form(
              child: TextFormField(
                controller: _controller,
                decoration: const InputDecoration(labelText: 'Send a message'),
              ),
            ),
            StreamBuilder(
              stream: widget.channel,
              builder: (context, snapshot) {
                if(snapshot.hasData) {
                  String decoded = utf8.decode(snapshot.data as Uint8List);
                  String token = decoded.substring(decoded.indexOf('key')+3,decoded.indexOf('.'));
                  globals.usersList[i].setToken(token);
                  print(decoded);
                  print(token);
                  i++;
                  print(globals.usersList);
                  setState(() {
                    
                  });
                  }
                return Padding(
                  padding: const EdgeInsets.symmetric(vertical: 24.0),
                  child: Text(snapshot.hasData ? snapshot.data.toString() : ''),
                );
              },
            )
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: (_sendMessage),
        tooltip: 'Send message',
        child: const Icon(Icons.send),
      ),
       // This trailing comma makes auto-formatting nicer for build methods.
    );
  }

  void _sendMessage() {
    if (_controller.text.isNotEmpty) {
      String sender = _controller.text;
      String registrationMessage = "{'register':'true', 'sender':'$sender'}";
      globals.usersList.add(new ChatUsers(sender));
      widget.channel.write(registrationMessage);
    }
  }


}```

And code of Navigator:
```floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
        floatingActionButton: Padding(
          padding: const EdgeInsets.all(20.0),
          child: Row(
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            children: <Widget>[
              FloatingActionButton(
                onPressed: () {
                  Navigator.push(
                      context,
                      MaterialPageRoute(
                          builder: (context) => RegisterScreen(widget.sock)));
                }, ```