Error entering two conditions in an if () for a user

I want only user1 to be able to enter User1.class but I get an error ... when I log in with the other users it does not give an error because they redirect me to StartActivity by not fulfilling the requirements of the if ...

This is the code

   public class LoginActivity extends AppCompatActivity {

    private EditText inputEmail, inputPassword;
    TextView emailadmin, passadmin;
    private FirebaseAuth auth;
    private ProgressBar progressBar;
    private Button btnSignup, btnLogin, btnReset;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
         //Get Firebase auth instance
        auth = FirebaseAuth.getInstance();

        if (auth.getCurrentUser() != null) {
            startActivity(new Intent(LoginActivity.this, InicioActivity.class));
            finish();
        }

        setContentView(R.layout.activity_login);
        inputEmail = (EditText) findViewById(R.id.email);
        inputPassword = (EditText) findViewById(R.id.password);
        emailadmin = (TextView) findViewById(R.id.emailadmin);
        passadmin = (TextView) findViewById(R.id.passadmin);
        emailadmin.setVisibility(View.INVISIBLE);
        passadmin.setVisibility(View.INVISIBLE);
        progressBar = (ProgressBar) findViewById(R.id.progressBar);
        btnSignup = (Button) findViewById(R.id.btn_signup);
        btnLogin = (Button) findViewById(R.id.btn_login);
        btnReset = (Button) findViewById(R.id.btn_reset_password);

        //Get Firebase auth instance
        auth = FirebaseAuth.getInstance();

        btnSignup.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(LoginActivity.this, SignupActivity.class));
            }
        });

        btnReset.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(LoginActivity.this, ResetPasswordActivity.class));
            }
        });

        btnLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                final String email = inputEmail.getText().toString();
                final String password = inputPassword.getText().toString();
                emailadmin.setText(email);
                passadmin.setText(password);

                if (TextUtils.isEmpty(email)) {
                    Toast.makeText(getApplicationContext(), "Ingresa tu correo electrónico", Toast.LENGTH_SHORT).show();
                    return;
                }

                if (TextUtils.isEmpty(password)) {
                    Toast.makeText(getApplicationContext(), "Ingresa tu contraseña", Toast.LENGTH_SHORT).show();
                    return;
                }

                progressBar.setVisibility(View.VISIBLE);

                //authenticate user

                auth = FirebaseAuth.getInstance();
                auth.signInWithEmailAndPassword(email, password)
                        .addOnCompleteListener(LoginActivity.this, new OnCompleteListener<AuthResult>() {
                            @Override
                            public void onComplete(@NonNull Task<AuthResult> task) {
                                // If sign in fails, display a message to the user. If sign in succeeds
                                // the auth state listener will be notified and logic to handle the
                                // signed in user can be handled in the listener.
                                progressBar.setVisibility(View.GONE);
                                if (!task.isSuccessful()) {
                                    // there was an error
                                    if (password.length() < 6) {
                                        inputPassword.setError(getString(R.string.minimum_password));
                                    } else {
                                        Toast.makeText(LoginActivity.this, getString(R.string.auth_failed), Toast.LENGTH_LONG).show();
                                    }
                                } else {
                                    if ((email.equals("[email protected]")) && (password.equals("usuario123"))) {
                                        Intent intent = new Intent(LoginActivity.this, Usuario1.class);
                                        startActivity(intent);
                                        finish();
                                } else {
                                    Intent intent = new Intent(LoginActivity.this, InicioActivity.class);
                                    startActivity(intent);
                                    finish();
                                }
                            }
                        }
            });
            }
        });
    }
}

And the Logcat is this

    E/AndroidRuntime: FATAL EXCEPTION: main
                  Process: com.example.matias.finalcode, PID: 27550
                  java.lang.NullPointerException: Attempt to invoke interface method 'void com.google.firebase.auth.FirebaseAuth$AuthStateListener.onAuthStateChanged(com.google.firebase.auth.FirebaseAuth)' on a null object reference
                      at com.google.firebase.auth.zzi.run(Unknown Source)
                      at android.os.Handler.handleCallback(Handler.java:739)
                      at android.os.Handler.dispatchMessage(Handler.java:95)
                      at android.os.Looper.loop(Looper.java:135)
                      at android.app.ActivityThread.main(ActivityThread.java:5258)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at java.lang.reflect.Method.invoke(Method.java:372)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:898)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693)
I/Process: Sending signal. PID: 27550 SIG: 9
Application terminated.