Firebug gives me the following error when going to the main page with debug=true while not logged in:
skin is not defined https://commons.wikimedia.org/w/index.php?title=MediaWiki:AnonymousI18N.js& action=raw&ctype=text/javascript Line 14
Note that the page flashes with content and then goes blank.
Version: 1.19
Severity: normal
URL: https://commons.wikimedia.org/wiki/Main_page?debug=true