Fix 2 possible NullPointer occurences

marco

2015-10-17 1aec17636d8c548257cb307f8cc1e41354e00421

 src/main/java/com/gitblit/wicket/ExternalImage.java

@@ -27,6 +27,7 @@
      super(id, new Model<String>(url));

   }



   @Override

   protected void onComponentTag(ComponentTag tag) {

      super.onComponentTag(tag);

      checkComponentTag(tag, "img");