Error: Call to a member function getEntityListForConfigItemSet() on null

I have not used the functionality for a while, but went to create a new set today and got this message. Here is the full string:

Error: Call to a member function getEntityListForConfigItemSet() on null in CRM_Civiconfig_Form_Edit->getTabs() (line 207 of /var/www/ct_drupal/sites/all/modules/civicrm/ext/configitems-2.0.0/CRM/Civiconfig/Form/Edit.php).

If I try to edit any of the two config sets I currently have, I get the exactly same issue and error message. I disabled and enabled the extension to see if that made a difference, but it did not. I'll see what I can see on my dev environment to see if I can get any more information.

I am running CiviCRM 5.57 on Drupal 7.94