Animated wand of animation works and animated wand of animation animating a wand of animation works (#95982)

## About The Pull Request

Fix 1: argument 4 on a new mimic is delete parent, not not having googly
eyes, so the issue there is clear

fix 2: `remove_thing_from_blackboard_key()` had no handling for the list
not yet being up, so it crashes thinking it's been called where
`clear_blackboard_key()` should've been.

fix 3: same as 1 but on wand of nothing, replaced copypaste with just
calling the function

## Why It's Good For The Game

fixes #95981
fixes an animated wand of animation animating a wand of animation
runtiming
Also the same problem with the wand of nothing

## Changelog
🆑

fix: animating a wand of animation works, and that animated wand of
animation animating a wand of animation does not runtime

/🆑

code/datums/ai/_ai_controller.dm

@@ -874,6 +874,8 @@ multiple modular subtrees with behaviors
  */
 /datum/ai_controller/proc/remove_thing_from_blackboard_key(key, thing)
 	var/associated_value = blackboard[key]
+	if(isnull(associated_value))
+		return
 	if(thing == associated_value)
 		stack_trace("remove_thing_from_blackboard_key was called un-necessarily in a situation where clear_blackboard_key would suffice. ")
 		clear_blackboard_key(key)