Can't sign in using Google or upvote/accept/comment

I can’t find a “meta” version of this site like StackExchange has, so hopefully it’s okay to post this question here.

Today I find that I am no longer able to log in through Google like I previously could. When I go to the sign-in page and click on the Google icon, nothing appears to happen. Closer examination reveals that the page actually reloads producing an identical look.

In the javascript console I see a LOT of errors:

Uncaught SyntaxError: Unexpected token !
(index):289 Uncaught ReferenceError: $ is not defined
(index):344 Uncaught ReferenceError: $ is not defined
jquery.validate.min.js?v=20:16 Uncaught ReferenceError: jQuery is not defined
jquery.openid.js?v=20:9 Uncaught ReferenceError: $ is not defined
(index):446 Uncaught ReferenceError: $ is not defined
(index):453 Uncaught ReferenceError: cleanUrl is not defined

So the site is broken? I had to “recover” my account to be able to log in, as I don’t have any other login methods other than through Google.

A bit further poking around when logged in via the “recover” option - I don’t seem to be able to upvote helpful answers, or accept, or comment on them.