The following exception (minor details changing) occurs from time to time:
[WahP2ApAAE0AAFxBIYsAAABF] /w/api.php?action=query&format=json&meta=languagestats&lslanguage=ar BannerExistenceException from line 351 of /srv/mediawiki/php-1.30.0-wmf.16/extensions/CentralNotice/includes/Banner.php: No banner exists where tmp_name = WikiCon. Could not load.
I believe this should not throw an exception that we log. Do we care that a banner doesn't exist? Does anyone other than RelEng look at these log entries? This particular one was from testwiki, but I do see them on meta from time to time.