Parsing cleanup

src/engine/objects/ItemTemplate.java

@@ -134,7 +134,8 @@ public class ItemTemplate {
         if (jsonObject.containsValue("item_bulk_factor"))
             item_bulk_factor = ((Double) jsonObject.get("item_bulk_factor")).floatValue();
 
-        item_defense_rating = ((Double) jsonObject.get("item_defense_rating")).floatValue();
+        if (jsonObject.containsValue("item_defense_rating"))
+            item_defense_rating = ((Double) jsonObject.get("item_defense_rating")).floatValue();
 
         JSONArray itemflags = (JSONArray) jsonObject.get("item_flags");