Flutter 类型“\u SyncIterable”不是类型“List”的子类型

我正在跟进谷歌的代码实验室

但这座建筑同样也在失败

我试着给出物体的类型。但还是失败了

// Copyright 2018 The Flutter team. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

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

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

// #docregion MyApp
class MyApp extends StatelessWidget {
  // #docregion build
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Startup Name Generator',
      theme: ThemeData(
        primaryColor: Colors.white,
      ),
      home: RandomWords(),
    );
  }
  // #enddocregion build
}
// #enddocregion MyApp

// #docregion RWS-var
class RandomWordsState extends State<RandomWords> {
  final _suggestions = <WordPair>[];
  final Set<WordPair> _saved = Set<WordPair>();
  final _biggerFont = const TextStyle(fontSize: 18.0);
  // #enddocregion RWS-var

  // #docregion _buildSuggestions
  Widget _buildSuggestions() {
    return ListView.builder(
        padding: const EdgeInsets.all(16.0),
        itemBuilder: /*1*/ (context, i) {
          if (i.isOdd) return Divider(); /*2*/

          final index = i ~/ 2; /*3*/
          if (index >= _suggestions.length) {
            _suggestions.addAll(generateWordPairs().take(10)); /*4*/
          }
          return _buildRow(_suggestions[index]);
        });
  }
  // #enddocregion _buildSuggestions

  // #docregion _buildRow
  Widget _buildRow(WordPair pair) {
    final bool alreadySaved = _saved.contains(pair);
    return ListTile(
      title: Text(
        pair.asPascalCase,
        style: _biggerFont,
      ),
      trailing: Icon(
        alreadySaved ? Icons.favorite : Icons.favorite_border,
        color: alreadySaved ? Colors.red : null,
      ),
      onTap: () {
        setState(() {
          if (alreadySaved) {
            _saved.remove(pair);
          } else {
            _saved.add(pair);
          }
        });
      },
    );
  }
  // #enddocregion _buildRow

  // #docregion RWS-build
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Startup Name Generator'),
        actions: <Widget>[
          IconButton(icon: Icon(Icons.list), onPressed: _pushSaved),
        ],
      ),
      body: _buildSuggestions(),
    );
  }
  // #enddocregion RWS-build

  void _pushSaved() {
    Navigator.of(context).push(
      MaterialPageRoute<void>(
        // Add 20 lines from here...
        builder: (BuildContext context) {
          final Iterable<ListTile> tiles = _saved.map(
            (WordPair pair) {
              return ListTile(
                title: Text(
                  pair.asPascalCase,
                  style: _biggerFont,
                ),
              );
            },
          );
          final List<Widget> divided = ListTile.divideTiles(
            context: context,
            tiles: tiles,
          ).toList();

          return Scaffold(
            appBar: AppBar(
              title: Text('Saved Suggestions'),
            ),
            body: ListView(children: divided),
          );
        },
      ),
    );
  }
  // #docregion RWS-var
}
// #enddocregion RWS-var

class RandomWords extends StatefulWidget {
  @override
  RandomWordsState createState() => RandomWordsState();
}

---

实际上我在这里运行了你的代码，我一点也没有得到那个错误

---

您共享的日志似乎发生在热重新加载期间。热重新加载有时会出现这样的错误，因为旧状态仍然存在。我想如果你再次运行你的应用程序，你就不会有问题了

错误具体指的是哪一行号？是的，我在同一个教程中遇到了完全相同的问题。重新启动应用程序有效。谢谢

Performing hot reload...
Syncing files to device Android SDK built for x86...
I/flutter ( 4807): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter ( 4807): The following assertion was thrown building Builder(dirty):
I/flutter ( 4807): type '_SyncIterable<Widget>' is not a subtype of type 'List<Widget>'
I/flutter ( 4807):