Do not print a stacktrace when failing to display the property of an Object from a page

This happens when calling $doc.display(String fieldname, String type, String pref, BaseObject obj, XWikiContext context) with a fieldname that doesn't exist in the passed object. In that case a stacktrace containing a NPE is logged. It would be better to have a nicer message such as :

Failed to display field [division] in [view] mode for Object [XWiki.Admin]