Remove Velocity error in logs when editing a class

09:28:52,986 ERROR P1-19 http://localhost:8080/xwiki/bin/edit/XWiki/PhotoAlbumClass?editor=class SimpleLog4JLogSystem:logVelocityMessage:154 - Left side ($request.xpage) of '==' operation has null value. If a reference, it may not be in the context. Operation not possible.  [line 1, column 21]