2
Ding, Ding, Ding, Ding! You've found the magic bug!
Just kidding. This is the first I'd seen of this error as well. After looking at the code, it looks like you have a ticket that was submitted by a user that has been deleted.
the current line 119 looks like this:
'uname'=>$user->getVar('uname'),
Try this line in its place:
'uname'=>(isset($user)?$user->getVar('uname'):$xoopsConfig['anonymous']),
I imagine that the same assumption will crop up in other places in xhelp, so consider this a stop-gap solution until I can test the rest of the application.