Error EntityMalformedException with multiple dependent field

I'm using a content type which have 3 fields depending on one another. The 3rd field causes an error:

EntityMalformedException : Missing bundle property on entity of type node. in entity_extract_ids() (ligne 7844 .../includes/common.inc).

I've found the lines 512 to 515 of the file reference_option_limit.module are causing the error:

  foreach ($entities as $entity) {
       list($id, $vid, $bundle) = entity_extract_ids($referred_entity_type, $entity);
       $options_limited[$id] = entity_label($referred_entity_type, $entity);
    }

Sometimes, this modifies the $entity variable the fonction receives as a parameter.
Renaming $entity solves the problem :

  foreach ($entities as $entity2) {
       list($id, $vid, $bundle) = entity_extract_ids($referred_entity_type, $entity2);
       $options_limited[$id] = entity_label($referred_entity_type, $entity2);
    }