Ошибка про работе с камерой андройд 6

Ошибка:

Attempt to get lenght of null array.

Помогите плиз не могу понять что с этими разрешениями не так:

private void CallCamera() {
  File folder = new File("sdcard/camera_app");
  if (!folder.exists()) {
    folder.mkdir();
  }
  File image_file = new File(folder, "cam_image.jpg");
  Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
  cameraIntent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(image_file));
  startActivityForResult(cameraIntent, CAM_REQUEST);
}

public void MakePhoto(View view) {
  if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
    CallCamera();
  } else {
    if (shouldShowRequestPermissionRationale(Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
      Toast.makeText(this, "Nu Avem Permis de salvare a imaginii", Toast.LENGTH_SHORT).show();
    }
    requestPermissions(new String[] {
      Manifest.permission.WRITE_EXTERNAL_STORAGE
    }, REQUEST_EXTERNAL_RESULT);
  }
}
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
  if (requestCode == REQUEST_EXTERNAL_RESULT) {
    if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
      CallCamera();
    } else {
      Toast.makeText(this, "Nu avem permis de a salva foto", Toast.LENGTH_SHORT).show();
    }
  } else {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
  }
}

public void onActivityResult(int requestCode, int resultCode, Intent data) {
  super.onActivityResult(requestCode, resultCode, data);
  // String path = "sdcard/camera_app/cam_image.jpg";
  // ImageView imageView;
  // imageView = (ImageView) findViewById(R.id.camera);
  // imageView.setImageDrawable(Drawable.createFromPath(path));
  Toast.makeText(this, "Succes!", Toast.LENGTH_SHORT).show();
}