Flutter + Firebase错误将匿名用户升级到GoogleSignIn（给出的字符串为空或null）

Question

我在Flutter中有一个匿名帐户，正在尝试使用Google的AuthCredential对其进行升级。我已验证凭据是使用有效的accessToken和idToken创建的。

因此，如果auth.currentUser()是我的匿名FirebaseUser，则在下面调用linkAccountToGoogle()会导致错误。

/// Upgrade an anonymous account by linking it to a Google account.
Future<FirebaseUser> linkAccountToGoogle() async {
  final credential = await _getGoogleAuthCredential();
  if (credential != null) {
    try {
      return auth.linkWithCredential(credential);  // <=== THROWS ERROR
    } catch (e) {
      print(e);
    }
  }
  return null;
}

/// Tries to sign-in silently first. May return `null`.
Future<AuthCredential> _getGoogleAuthCredential() async {
  GoogleSignInAccount account;
  try {
    account = await _googleAuthService.signInSilently() ??
        await _googleAuthService.signIn();
  } catch (e) {
    print(e);
  }
  final googleAuth = await account?.authentication;
  if (account == null) {
    print('Unable to retrieve Google account.');
  } else if (googleAuth == null) {
    print('Unable to authenticate to Google account (${account.email}).');
  } else {
    // print(
    //     'accessToken: ${googleAuth.accessToken}, idToken: ${googleAuth.idToken}');
    return GoogleAuthProvider.getCredential(
        accessToken: googleAuth.accessToken, idToken: googleAuth.idToken);
  }
  return null;
}

Stacktrace

I/flutter ( 3038): Credential: Instance of 'AuthCredential'
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038): Failed to handle method call
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038): java.lang.IllegalArgumentException: Given String is empty or null
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038):        at com.google.android.gms.common.internal.Preconditions.checkNotEmpty(Unknown Source:5)
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038):        at com.google.firebase.auth.EmailAuthProvider.getCredential(Unknown Source:2)
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038):        at io.flutter.plugins.firebaseauth.FirebaseAuthPlugin.handleLinkWithEmailAndPassword(FirebaseAuthPlugin.java:272)
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038):        at io.flutter.plugins.firebaseauth.FirebaseAuthPlugin.onMethodCall(FirebaseAuthPlugin.java:122)
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038):        at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler.onMessage(MethodChannel.java:200)
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038):        at io.flutter.view.FlutterNativeView$PlatformMessageHandlerImpl.handlePlatformMessage(FlutterNativeView.java:188)
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038):        at io.flutter.embedding.engine.FlutterJNI.handlePlatformMessage(FlutterJNI.java:202)
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038):        at android.os.MessageQueue.nativePollOnce(Native Method)
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038):        at android.os.MessageQueue.next(MessageQueue.java:325)
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038):        at android.os.Looper.loop(Looper.java:142)
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038):        at android.app.ActivityThread.main(ActivityThread.java:6694)
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038):        at java.lang.reflect.Method.invoke(Native Method)
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038):        at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
E/MethodChannel#plugins.flutter.io/firebase_auth( 3038):        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:769)
E/flutter ( 3038): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: PlatformException(error, Given String is empty or null, null)
E/flutter ( 3038): #0      StandardMethodCodec.decodeEnvelope (package:flutter/src/services/message_codecs.dart:564:7)
E/flutter ( 3038): #1      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:302:33)
E/flutter ( 3038): <asynchronous suspension>
E/flutter ( 3038): #2      FirebaseAuth.linkWithCredential (file:///home/jacob/.pub-cache/hosted/pub.dartlang.org/firebase_auth-0.8.0+1/lib/src/firebase_auth.dart:371:54)

我尝试过的事情

我要链接的Google帐户已经是该项目的用户，因此我从Firebase控制台中删除了该google用户。然后使用flutter clean flutter run再试一次。