Use correct serialization

src/engine/net/client/msg/BuyFromNPCWindowMsg.java

@@ -149,7 +149,7 @@ public class BuyFromNPCWindowMsg extends ClientNetMsg {
 
             for (Item item : sellInventory) {
                 try {
-                    Item.serializeForClientMsgForVendor(item, writer, sellPercent);
+                    Item.serializeForClientMsgForVendorWithoutSlot(item, writer, sellPercent);
                 } catch (Exception se) {
                     continue;
                 }