Another event: yes, the crow vanished as expected. There seems to be some randomness or another condition to that.
Note: Experienced the "Crow didn't vanish" several times. Deliberately let it hit the character, when the spawner is dead, the crow doesn't try to steal items, so it should be rather safe (the previous CTD in that case should have been fixed).
Note: Mirror's skeletons also don't vanish after the spawner is killed. However, it feels quiet fine, as skeletons don't steal items and usually there are other mirrors around.