Flutter项目突发Firebase相关编译错误求助

问题现象 #

原本运行正常的Flutter项目，返回后编译时触发Firebase相关错误，无法进入主函数，核心报错信息如下：

错误日志 #

Launching lib\main.dart on sdk gphone64 x86 64 in debug mode...
Running Gradle task 'assembleDebug'...
../../AppData/Local/Pub/Cache/hosted/pub.dev/firebase_ui_auth-1.14.0/lib/src/screens/internal/multi_provider_screen.dart:25:14: Error: A value of type 'List<AuthProvider<AuthListener, AuthCredential>>?' can't be returned from a function with return type 'List<AuthProvider<AuthListener, AuthCredential>>' because 'List<AuthProvider<AuthListener, AuthCredential>>?' is nullable and 'List<AuthProvider<AuthListener, AuthCredential>>' isn't.
 - 'List' is from 'dart:core'.
 - 'AuthProvider' is from 'package:firebase_ui_auth/src/providers/auth_provider.dart' ('../../AppData/Local/Pub/Cache/hosted/pub.dev/firebase_ui_auth-1.14.0/lib/src/providers/auth_provider.dart').
 - 'AuthListener' is from 'package:firebase_ui_auth/src/providers/auth_provider.dart' ('../../AppData/Local/Pub/Cache/hosted/pub.dev/firebase_ui_auth-1.14.0/lib/src/providers/auth_provider.dart').
 - 'AuthCredential' is from 'package:firebase_auth_platform_interface/src/auth_credential.dart' ('../../AppData/Local/Pub/Cache/hosted/pub.dev/firebase_auth_platform_interface-7.1.8/lib/src/auth_credential.dart').
      return _providers;
             ^

../../AppData/Local/Pub/Cache/hosted/pub.dev/vm_service-13.0.0/lib/src/vm_service.dart:314:30: Context: '_disposeHandler' couldn't be promoted because field promotion is only available in Dart 3.2 and above.
See http://dart.dev/go/non-promo-field-promotion-unavailable
  late final DisposeHandler? _disposeHandler;
                             ^
Target kernel_snapshot failed: Exception


FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:compileFlutterBuildDebug'.
> Process 'command 'C:\Flutter-Dart\flutter\bin\flutter.bat'' finished with non-zero exit value 1

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 14s
Error: Gradle task assembleDebug failed with exit code 1

已尝试无效操作 #

• 执行pub get/pub update
• 执行flutter clean后重建项目
• 重启Windows并重新打开项目
• 从GitHub拉取历史正常版本的项目副本，仍出现相同错误

解决方案 #

1. 升级Dart版本至3.2及以上 #

第二个错误明确提示当前Dart版本不支持字段提升特性，需升级Dart版本：

• 打开项目根目录的pubspec.yaml，修改environment字段：

  environment:
    sdk: '>=3.2.0 <4.0.0'
  

• 执行flutter pub get更新依赖

2. 调整firebase_ui_auth版本 #

第一个错误源于firebase_ui_auth-1.14.0的可空类型不匹配问题，需调整版本：

• 打开pubspec.yaml，修改firebase_ui_auth的版本：
  • 升级至最新稳定版：

    firebase_ui_auth: ^1.14.1 # 或更高兼容版本
    

  • 或降级至已知兼容版本：

    firebase_ui_auth: ^1.12.0
    

• 执行flutter pub get，随后执行flutter clean && flutter run

3. 清理全局Pub缓存（可选） #

若依赖缓存存在异常，执行以下命令清理：

flutter pub cache clean

清理完成后重新执行flutter pub get

内容的提问来源于stack exchange，提问作者APEGamer