More runtime errors

git-svn-id: http://tgstation13.googlecode.com/svn/trunk@1156 316c924e-a436-60f5-8080-3fe189b3f50e

code/modules/mob/living/carbon/human/human.dm

@@ -900,6 +900,9 @@
 			if (src.head)
 				for(var/i=1, i<=src.head.allowed.len, i++)
 			//		world << "[src.head.allowed[i]] and [W.type]"
+					if(!W)
+						src << "The code is under the impression that the item you're trying to stick in your hat doesn't exist."
+						return
 					if (findtext("[W.type]","[src.head.allowed[i]]") || istype(W, /obj/item/weapon/pen))
 						confirm = 1
 						break