We have a bean that has an image. When saving a new bean (not edit, only create), we get a fatal error, call to unknown method method delta() in the entity_property_getter_method() of the entity api module.
Fatal error: Call to undefined method Bean::delta() in sites\all\modules\entity\includes\entity.property.inc on line 354
Following the trace stack, bean save() => entity save() => filefield_paths_entity_update() => token_generate([bean:delta]) and things go bad.
I think if you move to using a machine code field for the delta field, then this error will simply disappear, otherwise, maybe setting the delta on validate could prevent this error (I have not tested this nor looked at the code)
Workaround: Create the bean and then upload the image :)