Well, when I try to access this link I get a 401 ;-)
So this is a "private" Trac, and all I can say is that they wrote a buggy TracLinks in their wiki page, something like:
[wiki:WikiStart?version=this-is-not-an-int]
WikiStart
As we don't do any kind of checking on the ?… params when creating the link, we can't prevent such a link to be written. Whether we should catch that error when the link is dereferenced and produce a nicer error instead of an internal error is another story, and that wouldn't solve your problem (and would take away my favorite recipe to trigger a backtrace and test the error page ;-) ).
So, best advice is to fix this buggy link (or ask those who can edit this page to do it).
