Google Maps Activity crash applicacion Android Stuido with dexter

Question

I followed a tutorial on YouTube to find on the map my location, but when I run the application, it closes. Does someone know why this happens?

uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"

uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"

implementation 'com.karumi:dexter:6.2.3'

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {

    LocationManager locationManager;
    LocationListener locationListener;
    LatLng userLatLong;

    private GoogleMap mMap;


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

        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;

        locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
        locationListener = new LocationListener() {
            @Override
            public void onLocationChanged(@NonNull Location location) {
                userLatLong = new LatLng(location.getLatitude(), location.getLongitude());
                mMap.clear();
                mMap.addMarker(new MarkerOptions().position(userLatLong).title("Minha Localização"));
                mMap.moveCamera(CameraUpdateFactory.newLatLng(userLatLong));
            }
        };

        askLocationPermission();

        /* Add a marker in Sydney and move the camera
        LatLng sydney = new LatLng(-34, 151);
        mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
        mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));*/
    }

    public void askLocationPermission() {
        Dexter.withActivity(this).withPermission(Manifest.permission.ACCESS_FINE_LOCATION).withListener(new PermissionListener() {
            @Override
            public void onPermissionGranted(PermissionGrantedResponse permissionGrantedResponse) {
                if (ActivityCompat.checkSelfPermission(getBaseContext(), Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getBaseContext(), Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                    return;
                }
                locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);

                Location lastLocation = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
                userLatLong = new LatLng(lastLocation.getLatitude(), lastLocation.getLongitude());
                mMap.clear();
                mMap.addMarker(new MarkerOptions().position(userLatLong).title("Minha Localização"));
                mMap.moveCamera(CameraUpdateFactory.newLatLng(userLatLong));
            }

            @Override
            public void onPermissionDenied(PermissionDeniedResponse permissionDeniedResponse) {

            }

            @Override
            public void onPermissionRationaleShouldBeShown(PermissionRequest permission, PermissionToken token) {
                token.continuePermissionRequest();
            }
        }).check();
    }
}

ERROR:

java.lang.NullPointerException: Attempt to invoke virtual method 'double android.location.Location.getLatitude()' on a null object reference
        at com.example.maps.MapsActivity$2.onPermissionGranted(MapsActivity.java:82)
        at com.karumi.dexter.MultiplePermissionsListenerToPermissionListenerAdapter.onPermissionsChecked(Unknown Source:35)
        at com.karumi.dexter.DexterInstance$1.run(Unknown Source:43)
        at com.karumi.dexter.MainThread.execute(Unknown Source:6)
        at com.karumi.dexter.DexterInstance.checkMultiplePermissions(Unknown Source:71)
        at com.karumi.dexter.DexterInstance.checkPermissions(Unknown Source:0)
        at com.karumi.dexter.Dexter.check(Unknown Source:10)
        at com.example.maps.MapsActivity.askLocationPermission(MapsActivity.java:97)
        at com.example.maps.MapsActivity.onMapReady(MapsActivity.java:64)
        at com.google.android.gms.maps.zzat.zzb(com.google.android.gms:play-services-maps@@18.0.0:1)
        at com.google.android.gms.maps.internal.zzaq.zza(com.google.android.gms:play-services-maps@@18.0.0:5)
        at com.google.android.gms.internal.maps.zzb.onTransact(com.google.android.gms:play-services-maps@@18.0.0:3)
        at android.os.Binder.transact(Binder.java:1079)
        at du.aZ(:com.google.android.gms.dynamite_mapsdynamite@212116082@21.21.16 (120406-0):2)
        at com.google.maps.api.android.lib6.impl.bk.run(:com.google.android.gms.dynamite_mapsdynamite@212116082@21.21.16 (120406-0):1)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:246)
        at android.app.ActivityThread.main(ActivityThread.java:8577)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:602)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1130)