Fix nullspaced closet runtime (#4964)

# About the pull request

![image](https://github.com/cmss13-devs/cmss13/assets/41448081/a87707be-a80e-4e72-b6ea-d98d4172de79)

code/game/objects/structures/crates_lockers/closets.dm

@@ -158,10 +158,15 @@
 
 
 /obj/structure/closet/proc/take_damage(damage)
+	if(health <= 0)
+		return
+
 	health = max(health - damage, 0)
 	if(health <= 0)
-		for(var/atom/movable/A as anything in src)
-			A.forceMove(src.loc)
+		for(var/atom/movable/movable as anything in src)
+			if(!loc)
+				break
+			movable.forceMove(loc)
 		playsound(loc, 'sound/effects/meteorimpact.ogg', 25, 1)
 		qdel(src)