When comparing two versions of the same object (with "Show diferences" in content/history) if one of the objects has an image attribute with an invalid image the page execution stops and we get this fatal error:

Call to a member function hasAttributes() on a non-object in /home/xmak/public_html/vkonline/kernel/classes/datatypes/ezxmltext/handlers/input/ezsimplifiedxmleditoutput.php on line 106

Steps to reproduce

1) create an object of class Article
2) somehow upload into it's image attribute (or smiulate) an invalid image
3) publish the article
4) re-edit the article and upload a valid image
5) go to "manage versions" for that article and compare version 1 and 2