On beta.wmflabs.org just discovered on Special:Preferences access.

What happens?:

• [YgPUS8ACOW2iBBEkTbtzjAAAAAQ]
• DomainException: HTMLForm::getField: no field named discussiontools-newtopictool

Backtrace:

• from /srv/mediawiki/php-master/includes/htmlform/HTMLForm.php(441)
• /srv/mediawiki/php-master/includes/htmlform/HTMLFormField.php(145): HTMLForm->getField(string)
• /srv/mediawiki/php-master/includes/htmlform/HTMLFormField.php(316): HTMLFormField->getNearestField(string, boolean)

What should have happened instead?:
No error messages. Special:Preferences applicable.