Early exit for no avail slots

src/engine/gameManager/ForgeManager.java

@@ -148,6 +148,9 @@ public enum ForgeManager implements Runnable {
             workOrder.completionTime = System.currentTimeMillis() + workOrder.rollingDuration;
             workOrder.slots_used = calcAvailableSlots(workOrder);
 
+            if (workOrder.slots_used == 0)
+                return 58;
+
             workOrder.total_produced = 0;
 
             // Single item configuration