https://en.wikipedia.org/w/api.php?uselang=user gives a error page instead of api help in the user lang. I am not sure, if this bug is in ULS or API.
If you report this error to the Wikimedia System Administrators, please include the details below.
PHP fatal error in /srv/mediawiki/php-1.25wmf5/extensions/UniversalLanguageSelector/UniversalLanguageSelector.hooks.php line 199:
Argument 3 passed to UniversalLanguageSelectorHooks::getLanguage() must be an instance of RequestContext, instance of ApiMain given
Version: master
Severity: normal