More constructor work.

src/engine/objects/ItemTemplate.java

@@ -107,7 +107,7 @@ public class ItemTemplate {
 
         JSONArray skills_used = (JSONArray) jsonObject.get("item_skill_used");
 
-        if (skills_used.isEmpty() == false)
+        if (skills_used != null)
             for (Object o : skills_used)
                 item_skill_used.add(Enum.CharacterSkills.valueOf((String) o));
     }