Error using FleatherTheme in Flutter 3.24.2

[yzxh24]

Steps to Reproduce

hi,bro, thanks for such a great extension that saves me a lot of development time.
In the process of using it I found a problem and need your help.
When I use FleatherTheme to set up fleather, I found that it doesn't work as expected, please see the screenshot I uploaded:

It looks a lot like a certain page without Scaffold, I've searched the community and found that other people can use it fine, I'm wondering if it's a difference caused by the flutter version?

This is my full code.

import 'dart:convert';
import 'dart:io';
import 'package:parchment/codecs.dart';

import 'package:fleather/fleather.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_localizations/flutter_localizations.dart';
import 'package:image_picker/image_picker.dart';
import 'package:url_launcher/url_launcher.dart';

void main() {
  runApp(const FleatherApp());
}

class FleatherApp extends StatelessWidget {
  const FleatherApp({super.key});

  @override
  Widget build(BuildContext context) => MaterialApp(
        localizationsDelegates: const [
          FleatherLocalizations.delegate,
          GlobalCupertinoLocalizations.delegate,
          GlobalMaterialLocalizations.delegate,
          GlobalWidgetsLocalizations.delegate
        ],
        supportedLocales: FleatherLocalizations.supportedLocales,
        debugShowCheckedModeBanner: false,
        theme: ThemeData.light(
          useMaterial3: false,
        ),
        darkTheme: ThemeData.dark(
          useMaterial3: false,
        ),
        title: 'Fleather - rich-text editor for Flutter',
        home: const HomePage(),
      );
}

class HomePage extends StatefulWidget {
  const HomePage({super.key});

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final FocusNode _focusNode = FocusNode();
  final GlobalKey<EditorState> _editorKey = GlobalKey();
  FleatherController? _controller;

  @override
  void initState() {
    super.initState();
    if (kIsWeb) BrowserContextMenu.disableContextMenu();
    _initController();
  }

  @override
  void dispose() {
    super.dispose();
    if (kIsWeb) BrowserContextMenu.enableContextMenu();
  }

  Future<void> _initController() async {
    try {
      final result = await rootBundle.loadString('assets/welcome.json');
      final heuristics = ParchmentHeuristics(
        formatRules: [],
        insertRules: [
          ForceNewlineForInsertsAroundInlineImageRule(),
        ],
        deleteRules: [],
      ).merge(ParchmentHeuristics.fallback);
      final doc = ParchmentDocument.fromJson(
        jsonDecode(result),
        heuristics: heuristics,
      );
      // final doc = ParchmentMarkdownCodec().decode(_markdown);

      _controller = FleatherController(document: doc);
    } catch (err, st) {
      if (kDebugMode) {
        print('Cannot read welcome.json: $err\n$st');
      }
      _controller = FleatherController();
    }
    setState(() {});
  }

  @override
  Widget build(BuildContext context) {
    final fleatherThemeFallback = FleatherThemeData.fallback(context);

    return Scaffold(
      appBar: AppBar(elevation: 0, title: const Text('Fleather Demo')),
      body: _controller == null
          ? const Center(child: CircularProgressIndicator())
          : Column(
              children: [
                FleatherToolbar.basic(
                    controller: _controller!, editorKey: _editorKey),
                Divider(height: 1, thickness: 1, color: Colors.grey.shade200),
                Expanded(
                  child: FleatherTheme(
                      data: fleatherThemeFallback,
                      child: FleatherEditor(
                        controller: _controller!,
                        focusNode: _focusNode,
                        editorKey: _editorKey,
                        padding: EdgeInsets.only(
                          left: 16,
                          right: 16,
                          bottom: MediaQuery.of(context).padding.bottom,
                        ),
                        onLaunchUrl: _launchUrl,
                        maxContentWidth: 800,
                        embedBuilder: _embedBuilder,
                        spellCheckConfiguration: SpellCheckConfiguration(
                            spellCheckService: DefaultSpellCheckService(),
                            misspelledSelectionColor: Colors.red,
                            misspelledTextStyle:
                                DefaultTextStyle.of(context).style),
                      )),
                ),
              ],
            ),
    );
  }

  Widget _embedBuilder(BuildContext context, EmbedNode node) {
    if (node.value.type == 'icon') {
      final data = node.value.data;
      // Icons.rocket_launch_outlined
      return Icon(
        IconData(int.parse(data['codePoint']), fontFamily: data['fontFamily']),
        color: Color(int.parse(data['color'])),
        size: 18,
      );
    }

    if (node.value.type == 'image') {
      final sourceType = node.value.data['source_type'];
      ImageProvider? image;
      if (sourceType == 'assets') {
        image = AssetImage(node.value.data['source']);
      } else if (sourceType == 'file') {
        image = FileImage(File(node.value.data['source']));
      } else if (sourceType == 'url') {
        image = NetworkImage(node.value.data['source']);
      }
      if (image != null) {
        return Padding(
          // Caret takes 2 pixels, hence not symmetric padding values.
          padding: const EdgeInsets.only(left: 4, right: 2, top: 2, bottom: 2),
          child: Container(
            width: 300,
            height: 300,
            decoration: BoxDecoration(
              image: DecorationImage(image: image, fit: BoxFit.cover),
            ),
          ),
        );
      }
    }

    return defaultFleatherEmbedBuilder(context, node);
  }

  void _launchUrl(String? url) async {
    if (url == null) return;
    final uri = Uri.parse(url);
    final canLaunch = await canLaunchUrl(uri);
    if (canLaunch) {
      await launchUrl(uri);
    }
  }
}

/// This is an example insert rule that will insert a new line before and
/// after inline image embed.
class ForceNewlineForInsertsAroundInlineImageRule extends InsertRule {
  @override
  Delta? apply(Delta document, int index, Object data) {
    if (data is! String) return null;

    final iter = DeltaIterator(document);
    final previous = iter.skip(index);
    final target = iter.next();
    final cursorBeforeInlineEmbed = _isInlineImage(target.data);
    final cursorAfterInlineEmbed =
        previous != null && _isInlineImage(previous.data);

    if (cursorBeforeInlineEmbed || cursorAfterInlineEmbed) {
      final delta = Delta()..retain(index);
      if (cursorAfterInlineEmbed && !data.startsWith('\n')) {
        delta.insert('\n');
      }
      delta.insert(data);
      if (cursorBeforeInlineEmbed && !data.endsWith('\n')) {
        delta.insert('\n');
      }
      return delta;
    }
    return null;
  }

  bool _isInlineImage(Object data) {
    if (data is EmbeddableObject) {
      return data.type == 'image' && data.inline;
    }
    if (data is Map) {
      return data[EmbeddableObject.kTypeKey] == 'image' &&
          data[EmbeddableObject.kInlineKey];
    }
    return false;
  }
}

Environment

• OS [Mac OS 13.6]
• Flutter version [3.24.2]
• Fleather version [1.9.0]