Bad argument passed to array_map() on MongoFailedJobProvider

[juanf]

When running php artisan queue:failed this error is thrown:

  [ErrorException]
  array_map(): Argument #2 should be an array

The problem lies on MongoFailedJobProvider::all().
If I change line 31 from this:
$all = $this->getTable()->orderBy('_id', 'desc')->get();
to this:
$all = $this->getTable()->orderBy('_id', 'desc')->get()->all();

Then it works ok (using Laravel 5.3).