Error logging into the database: remove from the app

I have problems with my database, I try to login but it takes me out of the app.

public class MainActivity extends AppCompatActivity {
    Button bt_Ingresar;
    Button bt_registrarse;

    EditText et_Nombre, et_Password;
    private Cursor fila;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        et_Nombre = findViewById(R.id.usuario_ET);
        et_Password = findViewById(R.id.password_ET);


        bt_registrarse = findViewById(R.id.registrar_BT);
        bt_registrarse.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent registroClass = new Intent(MainActivity.this, Registro.class);
                MainActivity.this.startActivity(registroClass);
            }
        });


        bt_Ingresar = findViewById(R.id.login_BT);
        bt_Ingresar.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                BaseHelper user = new BaseHelper(MainActivity.this, "Demo", null, 1);
                SQLiteDatabase db = user.getWritableDatabase();

                String usuario = et_Nombre.getText().toString();
                String password = et_Password.getText().toString();

                fila = db.rawQuery("SELECT  NOMBRE, PASSWORD FROM PERSONAS WHERE NOMBRE='"+usuario+"' AND PASSWORD='"+password+"'", null);

                if(fila.moveToFirst()){
                    String usua = fila.getString(1);
                    String pass = fila.getString(2);

                    if (usuario.equals(usua) && password.equals(pass)){
                        Intent intent = new Intent(MainActivity.this, twoMain.class);

                        startActivity(intent);
                        et_Nombre.setText("");
                        et_Password.setText("");
                    }
                }
                else{
                    Toast.makeText(MainActivity.this, "Error al ingresar datos", Toast.LENGTH_SHORT).show();
                }
            }
        });


    }//end onCreate

// * tener en cuenta los espacios
}