使用Flutter进行网络构建时，引发了另一个异常：NoSuchMethodError：null上的无效成员：'findRenderObject'继续发生

Question

使用Flutter执行HotRestart时，引发了另一个异常。 NoSuchMethodError：无效的空成员：'findRenderObject'继续引发。

在“ flutter run”后立即出现此错误，但是如果重写文本中的字符，将输出以下错误。

我尝试重新启动Google Chrome，重新运行Flutter，更新FlutterSDK，重新启动VisualStudioCode，并在Android模拟器而非网络上进行构建，但是此错误从未消失。

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'todo_list_for_web',
      theme: ThemeData(
        primarySwatch: Colors.grey,
      ),
      home: RootPage(),
    );
  }
}

class RootPage extends StatefulWidget {
  @override
  _RootPageState createState() => _RootPageState();
}

class _RootPageState extends State<RootPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("Flutter Todo list"),
          backgroundColor: Colors.black87,
        ),
        body: Row(
          children: <Widget>[
            Expanded(
              flex: 5,
              child: Container(
                height: double.infinity,
                width: double.infinity,
                color: Colors.white,
                child: TaskListArea(),
              ),
            ),
            Expanded(
              flex: 3,
              child: Container(
                child: InfoWindows(),
              ),
            )
          ],
        ));
  }
}

class TaskListArea extends StatefulWidget {
  @override
  _TaskListAreaState createState() => _TaskListAreaState();
}

class _TaskListAreaState extends State<TaskListArea> {
  List<String> tasks = [
    "try making coffee",
    "work on homework",
    "do my paper",
  ];

  @override
  Widget build(BuildContext context) {
    return Container(
        color: Colors.green,
        child: Stack(children: <Widget>[
          Align(
            alignment: Alignment.topLeft,
            child: Padding(
                //Title Text
                padding: EdgeInsets.only(top: 18.0, left: 10.0, bottom: 30.0),
                child: Text(
                  "Today's tasks.",
                  style: TextStyle(
                    fontSize: 30.0,
                  ),
                  textAlign: TextAlign.start,
                )),
          ),
          Align(
              alignment: Alignment.center,
              child: Container(
                height: 300.0,
                child: ListView.separated(
                    separatorBuilder: (context, index) =>
                        Divider(color: Colors.black),
                    padding: EdgeInsets.all(16.0),
                    itemCount: tasks.length,
                    itemBuilder: (context, i) => Padding(
                      padding: EdgeInsets.all(8.0),
                      child: Center(child: Text(tasks[i]),)
                    )
                )
              )
          ),
          Padding(
              padding: EdgeInsets.all(50.0),
              child: Align(
                  alignment: Alignment.bottomCenter,
                  child: Row(children: <Widget>[
                    Expanded(
                        flex: 20,
                        child: TextField(
                          decoration: InputDecoration(
                              hintText: "make coffee.",
                              border: UnderlineInputBorder(
                                borderSide: BorderSide(color: Colors.black),
                              )),
                        )),
                    Expanded(
                      child: SizedBox(
                        width: 10.0,
                      ),
                    ),
                    Expanded(
                        flex: 5,
                        child: FlatButton(
                          color: Colors.grey,
                          onPressed: () {},
                          child: Text("Add"),
                        ))
                  ])))
        ]));
  }
}

class InfoWindows extends StatefulWidget {
  @override
  _InfoWindowsState createState() => _InfoWindowsState();
}

class _InfoWindowsState extends State<InfoWindows> {
  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        Expanded(
            flex: 1,
            child: Container(
              color: Colors.red,
            )),
        Expanded(
            flex: 1,
            child: Container(
              color: Colors.blueGrey,
            ))
      ],
    );
  }
}

执行热重启...

Another exception was thrown: NoSuchMethodError:invalid member on null: 'findRenderObject'      
Performing hot restart...

Restarted application in 509ms.
Performing hot restart...
                   511ms
══╡ EXCEPTION CAUGHT BY ANIMATION LIBRARY
╞═════════════════════════════════════════════════════════
The following JSNoSuchMethodError was thrown
while notifying listeners for
AnimationController:
NoSuchMethodError: invalid member on null:      
'findRenderObject'

When the exception was thrown, this was the     
stack:
package:flutter/src/widgets/editable_text.dart  
1726:68            get renderEditable
package:flutter/src/widgets/editable_text.dart  
1590:20            [_onCursorColorTick]
package:flutter/src/animation/listener_helpers.dart 124:21        notifyListeners
package:flutter/src/animation/animation_controller.dart 362:5     set value
package:flutter/src/widgets/editable_text.dart
1625:37            [_cursorTick]
package:build_web_compilers/src/dev_compiler/dart_sdk.js 28721:9  <fn>

The AnimationController notifying listeners was:AnimationController#2e5b8(⏭ 1.000; paused)      
════════════════════════════════════════════════════════════════════════════════════════════════════
Another exception was thrown: NoSuchMethodError:invalid member on null: 'findRenderObject'