initial instantiation causes a fatal error

The first time I drop an entity box in a region using Context UI, I get the following fatal error as a response to the AJAX call:

Fatal error: Call to a member function options_form() on a non-object in /blabla/d7/drupal/sites/all/modules/maintenance/boxes/boxes.module on line 427

Clearing cache a couple of times solves this, but I'm putting this here so it's flagged.