Allows clings to regenerate without a brain. (#19856)

* Move brain organ code where it belongs

* Rename too

* WIP, but hey, it kinda works now.

* Account for a few missing heads

* Remove vital check, killing the user on death

* Let defibs and scanners better deal with these

* Remove debug brains

* Clean up some more contingencies

* More head checks

* Update code/modules/antagonists/changeling/datum_changeling.dm

Co-authored-by: Farie82 <farie82@users.noreply.github.com>

* Fixes up signal business

* some stuff from sean's review

* Add some type safety checks for heads

* oops

* Update code/game/objects/items/weapons/cosmetics.dm

get this in there too

Co-authored-by: S34N <12197162+S34NW@users.noreply.github.com>

* Remove decap sword

* Quick suggestions

Co-authored-by: Ryan <80364400+Sirryan2002@users.noreply.github.com>

* Addresses shedding problems

* Add new defib changes

* this is why we have CI

Co-authored-by: Farie82 <farie82@users.noreply.github.com>
Co-authored-by: S34N <12197162+S34NW@users.noreply.github.com>
Co-authored-by: Ryan <80364400+Sirryan2002@users.noreply.github.com>

code/game/objects/structures/guillotine.dm

@@ -108,7 +108,7 @@
 
 		var/obj/item/organ/external/head/head = H.get_organ("head")
 
-		if(QDELETED(head))
+		if(QDELETED(head) || !istype(head))
 			blade_status = GUILLOTINE_BLADE_DROPPED
 			icon_state = "guillotine"
 			return