This code looks broken to me;
```
$this->allPreferences = Preferences::getPreferences( $this->getUser(), $this->getContext() );
```
found in `includes/specials/SpecialPreferencesList.php`. There is no such class as `Preferences` in this code base but only `PreferencesListPreferences` class exists with a `getPreferences()` definition.
Also, I see that calls to `getPreferences()` have been made in other places with;
```
$thisUsersPreferences = PreferencesListPreferences::getPreferences( $user, $preferenceNames, $context );
```
in `includes/PreferencesList.php`.
Noticed after submitting: https://gerrit.wikimedia.org/r/c/mediawiki/extensions/PreferencesList/+/514112 which caused this failure: https://integration.wikimedia.org/ci/job/quibble-vendor-mysql-hhvm-docker/51671/console.
NOTE: Also, the extension doesn't have a workboard/component/project board yet so will just use #mediawiki-extensions-general