Issue #1559826 by dww: Indicate dependency on Drupal core > 7.14
Avoid causing crashes in views ui and other things that try and grab an allowed values list.
Bug out of if there is no entity id.
Bug out if there is no entity.
Type out ['settings']['entityreference_field'] and ['settings'] itself only once.
Drupal is a registered trademark of Dries Buytaert.