使用 Firebase 时应用启动时的`_CastError（用于空值的空检查运算符）`答案

【问题标题】：`_CastError (Null check operator used on a null value)` on app launch when using Firebase使用 Firebase 时应用启动时的`_CastError（用于空值的空检查运算符）`
【发布时间】：2022-01-12 05:29:09
【问题描述】：

我使用新的flutterfire_cli 设置我的应用程序：

Future<void> main() async {
  await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);
  runApp(MyApp());
}

我尝试启动我的应用，但在应用启动时出现此异常：

E/flutter ( 1081): [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: Null check operator used on a null value
E/flutter ( 1081): #0      MethodChannel.binaryMessenger
package:flutter/…/services/platform_channel.dart:132
E/flutter ( 1081): #1      MethodChannel._invokeMethod
package:flutter/…/services/platform_channel.dart:157
E/flutter ( 1081): #2      MethodChannel.invokeMethod
package:flutter/…/services/platform_channel.dart:340
E/flutter ( 1081): #3      MethodChannel.invokeListMethod
package:flutter/…/services/platform_channel.dart:353
E/flutter ( 1081): #4      MethodChannelFirebase._initializeCore
package:firebase_core_platform_interface/…/method_channel/method_channel_firebase.dart:31
E/flutter ( 1081): #5      MethodChannelFirebase.initializeApp
package:firebase_core_platform_interface/…/method_channel/method_channel_firebase.dart:73
E/flutter ( 1081): #6      Firebase.initializeApp
package:firebase_core/src/firebase.dart:42
E/flutter ( 1081): #7      main
package:gatch_app/main_dev.dart:9
E/flutter ( 1081): #8      _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:129:25)
E/flutter ( 1081): #9      _rootRun (dart:async/zone.dart:1428:13)
E/flutter ( 1081): #10     _CustomZone.run (dart:async/zone.dart:1328:19)
E/flutter ( 1081): #11     _runZoned (dart:async/zone.dart:1863:10)
E/flutter ( 1081): #12     runZonedGuarded (dart:async/zone.dart:1851:12)
E/flutter ( 1081): #13     _runMainZoned.<anonymous closure> (dart:ui/hooks.dart:125:5)
E/flutter ( 1081): #14     _delayEntrypointInvocation.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:297:19)
E/flutter ( 1081): #15     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:192:12)
E/flutter ( 1081):
Reloaded 2 of 573 libraries in 1,090ms.

【问题讨论】：

标签： firebase flutter dart

【解决方案1】：

你需要先运行WidgetsFlutterBinding.ensureInitialized();

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();

  await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);
  runApp(MyApp());
}

【讨论】：