Fixes cryopod item preservation runtimes

Cryopods attempt to preserve certain important items when despawning
their occupants. They also attempt to remove the contents of anything on
their occupants. Some preserved items have important contents, which
should not be removed, and may cause runtimes after retrieval. This
should fix those runtimes.

code/game/machinery/cryopod.dm

@@ -307,6 +307,13 @@
 		W.loc = src
 
 		if(W.contents.len) //Make sure we catch anything not handled by del() on the items.
+			var/preserve = null
+			for(var/T in preserve_items)
+				if(istype(W,T))
+					preserve = 1
+					break
+			if(preserve) // Don't remove the contents of things that need preservation
+				continue
 			for(var/obj/item/O in W.contents)
 				if(istype(O,/obj/item/weapon/tank)) //Stop eating pockets, you fuck!
 					continue