Merge pull request #3158 from Citadel-Station-13/upstream-merge-31298

[MIRROR] Fixes crafting stacks without breaking crafted machinery

code/game/objects/items/stacks/stack.dm

@@ -151,7 +151,11 @@
 			if(!building_checks(R, multiplier))
 				return
 
-		var/obj/O = new R.result_type()
+		var/obj/O
+		if(R.max_res_amount > 1) //Is it a stack?
+			O = new R.result_type(usr.drop_location(), R.res_amount * multiplier)
+		else
+			O = new R.result_type(usr.drop_location())
 		O.setDir(usr.dir)
 		use(R.req_amount * multiplier)
 
@@ -164,16 +168,11 @@
 			W.ini_dir = W.dir
 		//END: oh fuck i'm so sorry
 
-		//is it a stack ?
-		if (R.max_res_amount > 1)
-			var/obj/item/stack/new_item = O
-			new_item.amount = R.res_amount*multiplier
-			new_item.update_icon()
+		if (QDELETED(O))
+			return //It's a stack and has already been merged
 
 		if (isitem(O))
 			usr.put_in_hands(O)
-		else
-			O.forceMove(usr.drop_location())
 		O.add_fingerprint(usr)
 
 		//BubbleWrap - so newly formed boxes are empty