Null check for vendor workorder lookup.

src/engine/gameManager/NPCManager.java

@@ -525,6 +525,9 @@ public enum NPCManager {
 
         ConcurrentHashMap.KeySetView<WorkOrder, Boolean> vendorWorkOrders = ForgeManager.vendorWorkOrderLookup.get(npc);
 
+        if (vendorWorkOrders == null)
+            return itemList;
+
         for (WorkOrder workOrder : vendorWorkOrders)
             itemList.addAll(workOrder.cooking);