BaseRepository::sync error

In my controller:
```php
$entity = $this->repository->update($request->all(), $id);
$this->repository->sync($id, 'departments', $request->get('departments'));
```
So I got the error:
```
Call to a member function departments() on array
```

Then I checked in line:
https://github.com/andersao/l5-repository/blob/master/src/Prettus/Repository/Eloquent/BaseRepository.php#L298

And the method "find" returns an array.