Fixes a NullPointerException and the default value of successSalvagedMessage

src/main/java/net/knarcraft/blacksmith/command/EditCommand.java

@@ -131,7 +131,7 @@ public abstract class EditCommand<K extends CustomTrait<L>, L extends Setting> i
             }
             settings.changeValue(setting, newValue);
             BlacksmithPlugin.getStringFormatter().displaySuccessMessage(sender,
-                    getValueChangedMessage(setting.getCommandName(), newValue));
+                    getValueChangedMessage(setting.getCommandName(), String.valueOf(newValue)));
             //Save the changes immediately to prevent data loss on server crash
             CitizensAPI.getNPCRegistry().saveToStore();
         }