Bring action tries to infer object location from type when type=reference

[rokusottervanger]

Configuring action Bring with semantics

{
  'action': 'bring', 
  'object': {'type': 'reference'}, 
  'target-location': {'id': 'flight_case'}
}

and knowledge

{}

Results in an exception because:

No source given, trying to find at default location.

And the type of the object is reference, which cannot be found.