Runtime fix for db_click when clicking the mask inventory slot with an empty hand. This proc will get rewritten anyway (when I've gathered enough courage and/or vodka :3)

git-svn-id: http://tgstation13.googlecode.com/svn/trunk@3907 316c924e-a436-60f5-8080-3fe189b3f50e

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

@@ -1026,6 +1026,8 @@ It can still be worn/put on as normal.
 				if(emptyHand)
 					wear_mask.DblClick()
 				return
+			if (!istype(W, /obj/item))
+				return
 			if (!( W.slot_flags & SLOT_MASK ))
 				return
 			u_equip(W)