New behaviour (see comment below from Thu, Sep 24, 10:26 AM PDT).
Old problem follows:
When I'm logged in as https://www.mediawiki.org/wiki/User:Thesquirrelsareattackingagain (test account), on mediawiki.org,
- clicking on the flyout badge, sends me to Special:Notifications
- going to https://www.mediawiki.org/wiki/Topic:S9ioxqczzxrpzjan (one of the 3 edits this account has made on mediawiki.org)
both of which result in:
Exception encountered, of type "Exception"
The webconsole (even with ?debug=1) just lists: GET https://www.mediawiki.org/wiki/Topic:S9ioxqczzxrpzjan [HTTP/1.1 200 OK 307ms]
I can't reproduce this with other accounts, nor with the testaccount on other wikis or on any other pages on mediawiki.org.
I tried a purge, and also resetting my userpreferences, but neither helped.
(possibly related to T73325: Special:Notifications throws Exception, found via searching for that error message)