Ошибка авторизации через google

Устанавлиаю на одну активити весь код для авторизации через гугл (firebase)

public class LoginActivity extends AppCompatActivity{
private FirebaseAuth mAuth;
private SignInButton signInButton;
private FirebaseAuth.AuthStateListener mAuthListener;
private GoogleApiClient mGoogleApiClient;
private static final int RC_SIGN_IN = 1;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);
    mAuth = FirebaseAuth.getInstance();
    signInButton = (SignInButton) findViewById(R.id.sign_in_button);
    mAuthListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            if(firebaseAuth.getCurrentUser() != null) {
                startActivity(new Intent(LoginActivity.this, MainActivity.class));
            }
        }
    };
    GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
            .requestIdToken(getString(R.string.default_web_client_id))
            .requestEmail()
            .build();
    mGoogleApiClient = new GoogleApiClient.Builder(getApplicationContext())
            .enableAutoManage(this, new GoogleApiClient.OnConnectionFailedListener() {
                @Override
                public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
                    Toast.makeText(LoginActivity.this, "Connection Failed", Toast.LENGTH_SHORT).show();
                }
            })
            .addApi(Auth.GOOGLE_SIGN_IN_API, gso)
            .build();
    signInButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            signIn();
        }
    });
}

@Override
protected void onStart() {
    super.onStart();
    mAuth.addAuthStateListener(mAuthListener);
}
private void signIn() {
    Intent signInIntent = Auth.GoogleSignInApi.getSignInIntent(mGoogleApiClient);
    startActivityForResult(signInIntent, RC_SIGN_IN);
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == RC_SIGN_IN) {
        GoogleSignInResult result = Auth.GoogleSignInApi.getSignInResultFromIntent(data);
        if (result.isSuccess()) {
            GoogleSignInAccount account = result.getSignInAccount();
            firebaseAuthWithGoogle(account);
        } else {
        }
    }
}
private void firebaseAuthWithGoogle(GoogleSignInAccount account) {
    AuthCredential credential = GoogleAuthProvider.getCredential(account.getIdToken(), null);
    mAuth.signInWithCredential(credential)
            .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    if (task.isSuccessful()) {
                        Log.d("TAG", "signInWithCredential:success");
                        FirebaseUser user = mAuth.getCurrentUser();
                    } else {
                        Log.w("TAG", "signInWithCredential:failure", task.getException());
                        Toast.makeText(LoginActivity.this, "Authentication failed.",
                                Toast.LENGTH_SHORT).show();
                    }
                }
            });
}
}

Все работает. Вс ок. Но когда пытаюсь установить на другой активити кнопку выхода (logout) приложение падает.

Вот код который добавляю на вторую активити

private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAuth = FirebaseAuth.getInstance();
}
@Override
protected void onStart() {
super.onStart();
mAuth.addAuthStateListener(mAuthList);
}

А вот ошибка, которую в итоге получаю

08-02 22:26:46.584 9197-9197/m.masyuk.com.fb.stackinfo E/AndroidRuntime: FATAL EXCEPTION: main
                                                                     Process: m.masyuk.com.fb.stackinfo, PID: 9197
                                                                     java.lang.NullPointerException: Attempt to invoke interface method 'void com.google.firebase.auth.FirebaseAuth$AuthStateListener.onAuthStateChanged(com.google.firebase.auth.FirebaseAuth)' on a null object reference
                                                                         at com.google.firebase.auth.zzg.run(Unknown Source)
                                                                         at android.os.Handler.handleCallback(Handler.java:751)
                                                                         at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                         at android.os.Looper.loop(Looper.java:154)
                                                                         at android.app.ActivityThread.main(ActivityThread.java:6077)
                                                                         at java.lang.reflect.Method.invoke(Native Method)
                                                                         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
                                                                         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)

Подскажите пожалуйста что я не так делаю.