添加Firebase身份验证后Android应用程序崩溃

// Project-level build.gradle
buildscript {
    dependencies {
        classpath 'com.google.gms:google-services:4.3.10'
    }
}

// App-level build.gradle
apply plugin: 'com.google.gms.google-services'

dependencies {
    implementation 'com.google.firebase:firebase-auth:21.0.1'
}

import com.google.firebase.FirebaseApp;
import com.google.firebase.auth.FirebaseAuth;

public class MyApplication extends Application {
    @Override
    public void onCreate() {
        super.onCreate();
        FirebaseApp.initializeApp(this);
    }
}

<uses-permission android:name="android.permission.INTERNET"/>

FirebaseAuth mAuth = FirebaseAuth.getInstance();
if (mAuth != null) {
    mAuth.signInWithEmailAndPassword(email, password)
        .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
            @Override
            public void onComplete(@NonNull Task<AuthResult> task) {
                if (task.isSuccessful()) {
                    // 登录成功
                } else {
                    // 登录失败
                }
            }
        });
} else {
    Log.e("FirebaseAuth", "FirebaseAuth instance is null");
}