这段代码昨天还在运行，今天又试图运行，突然出现了这个错误。
我可以在我的firebase用户数据库中看到，我试图创建的邮件用户正在被创建。如我的日志所述（从firebase预定义）：“电子邮件地址已被另一个帐户使用”。我不明白的是，为什么我得到一个空指针，它找不到用户，因此不发送验证电子邮件。它怎么可能是空的，而且还说已经有一个帐户与该电子邮件？
相关代码：

//Method for signing up a new user
    public void signUp(String email, String pwd, Context context, Activity activity){
        //Listener which gives response when the createUser method has run
        mContext = context;
        mActivity = activity;
        auth.createUserWithEmailAndPassword(email, pwd)
                .addOnCompleteListener(mActivity, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if (task.isSuccessful()) {
                            Log.i(TAG, "createUserWithEmail:success");
                            FirebaseUser user = auth.getCurrentUser();
                            if (user != null) {
                            user.sendEmailVerification()
                                    .addOnCompleteListener(new OnCompleteListener<Void>() {
                                        @Override
                                        public void onComplete(@NonNull Task<Void> task) {
                                            if (task.isSuccessful()) {
                                                Log.i(TAG, "Verification Email sent.");
                                                CreateNewUserActivity cna = new CreateNewUserActivity();
                                                cna.visibel();
                                            }
                                        }
                                    });
                            }

                        } else {
                            Toast.makeText(mContext, "Sign-up failed.", Toast.LENGTH_SHORT).show();
                            Log.i(TAG, "onComplete: " + task.getException());
                        }
                    }

                });
    }

更相关的代码：

public void setupAuthStateListener(final MainActivity activity) {
        auth.addIdTokenListener(new FirebaseAuth.IdTokenListener() {
            @Override
            public void onIdTokenChanged(@NonNull FirebaseAuth firebaseAuth) {
                if (firebaseAuth.getCurrentUser() != null){
                    if (firebaseAuth.getCurrentUser().isEmailVerified()){
                        auth.removeIdTokenListener(this);
                        firebaseHandler.loadDB();
                        Log.i(TAG, "Signed in from firebase");
                        Intent intent = new Intent(activity, MenuActivity.class);
                        activity.finish();
                        activity.startActivity(intent);
                    }else{
                        auth.signOut();
                        Toast.makeText(activity, "Your email is not verified. Verify the email to log in.", Toast.LENGTH_LONG).show();
                        Log.i(TAG, "onIdTokenChanged: Email not verified");
                    }
                }else {
                    Log.i(TAG, "Signed out of firebase");
                }
            }
        });
    }

日志：

2021-01-07 09:53:25.004 4117-4117/studios.kundby.fitnessapp I/AuthManager: onIdTokenChanged: Email not verified
2021-01-07 09:53:25.007 4117-4117/studios.kundby.fitnessapp I/AuthManager: onComplete: java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.gms.internal.firebase-auth-api.zzwg com.google.firebase.auth.FirebaseUser.zze()' on a null object reference
2021-01-07 09:53:25.007 4117-4117/studios.kundby.fitnessapp I/AuthManager: Signed out of firebase
2021-01-07 09:53:25.077 4117-4330/studios.kundby.fitnessapp I/chatty: uid=10080(studios.kundby.fitnessapp) RenderThread identical 1 line
2021-01-07 09:53:34.811 4117-4169/studios.kundby.fitnessapp W/System: Ignoring header X-Firebase-Locale because its value was null.
2021-01-07 09:53:35.000 4117-4117/studios.kundby.fitnessapp I/AuthManager: onComplete: com.google.firebase.auth.FirebaseAuthUserCollisionException: The email address is already in use by another account.
2021-01-07 09:53:36.497 4117-4169/studios.kundby.fitnessapp W/System: Ignoring header X-Firebase-Locale because its value was null.