"Unfortunately MyApp has stopped" error when clicking the application button

I'm running my app on Genymotion, developing on Android Studio.

Every time I run my application I click on the button to register, but when I click, I find the following message "Unfortunately MyApp has stopped", where after the application is finished.

Note: I am using Firebase to register data

Code of my Activity

    package com.example.matheus.MyApp;

    import android.content.Intent;
    import android.support.annotation.NonNull;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.Toast;

    import com.google.android.gms.tasks.OnCompleteListener;
    import com.google.android.gms.tasks.Task;
    import com.google.firebase.auth.AuthResult;
    import com.google.firebase.auth.FirebaseAuth;
    import com.google.firebase.auth.FirebaseUser;

public class CadastroActivity extends AppCompatActivity  {

    private Button mCadastro;
    private EditText mEmail, mSenha;
    private FirebaseAuth mAuth;
    private FirebaseAuth.AuthStateListener firebaseAuthStateListener;

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

        mAuth = FirebaseAuth.getInstance();
        firebaseAuthStateListener = new FirebaseAuth.AuthStateListener() {
            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                final FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
                if (user !=null){
                    Intent intent = new Intent(CadastroActivity.this, MainActivity.class);
                    startActivity(intent);
                    finish();
                    return;
                }
            }
        };

        mCadastro = (Button) findViewById(R.id.cadastrar);

        mEmail = (EditText) findViewById(R.id.email);
        mSenha = (EditText) findViewById(R.id.senha);

        mCadastro.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                final String email = mEmail.getText().toString();
                final String senha = mSenha.getText().toString();


      //linha 56 AQUI          mAuth.createUserWithEmailAndPassword(email, senha).addOnCompleteListener(CadastroActivity.this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        if (!task.isSuccessful()){
                            Toast.makeText(CadastroActivity.this, "Cadastrado com sucesso! Efetue o login", Toast.LENGTH_SHORT).show();

                        }
                    }
                });
            }
        });

    }


    @Override
    protected void onStart() {
        super.onStart();
        mAuth.addAuthStateListener(firebaseAuthStateListener);
    }

    @Override
    protected void onStop() {
        super.onStop();
        mAuth.removeAuthStateListener(firebaseAuthStateListener);
    }
}

Code where you detail where the error is:

  

02-17 13: 27: 45,439 1961-1961 / com.example.matheus.MyApp   E / AndroidRuntime: FATAL EXCEPTION: main                                                                                 Process: com.example.matheus.MyApp, PID: 1961                                                                                 java.lang.NullPointerException                                                                                     at com.google.android.gms.internal.zzdtp.zzb (Unknown Source)                                                                                     at com.google.android.gms.internal.zzdtw.zza (Unknown Source)                                                                                     at   com.google.firebase.auth.FirebaseAuth.createUserWithEmailAndPassword (Unknown   Source)                                                                                     at   com.example.matheus.MyApp.CadastroActivity $ 2.onClick (CadastroActivity.java:56)                                                                                     at android.view.View.performClick (View.java:4438)                                                                                     at android.view.View $ PerformClick.run (View.java:18422)                                                                                     at android.os.Handler.handleCallback (Handler.java:733)                                                                                     at android.os.Handler.dispatchMessage (Handler.java:95)                                                                                     at android.os.Looper.loop (Looper.java:136)                                                                                     at android.app.ActivityThread.main (ActivityThread.java:5001)                                                                                     at java.lang.reflect.Method.invokeNative (Native Method)                                                                                     at java.lang.reflect.Method.invoke (Method.java:515)                                                                                     at   com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run (ZygoteInit.java:785)                                                                                     at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:601)                                                                                     at dalvik.system.NativeStart.main (Native Method)