The file usage contains a link to ar.wikipedia.org in the namespace 104.
This namespace is not known to en.wikipedia.org, so when trying to format this link in FileUsage.prototype.getFileUrl(), the script throws an exception inside mw.Title.
Full stacktrace in: http://pastebin.com/xjhMxQsR
Version: master
Severity: normal
URL: https://en.wikipedia.org/wiki/Linux_distributions?debug=true#mediaviewer/File:Linux_Distribution_Timeline.svg