CB

Joomla load function will output a warning that user id doesn't exist if load is called with a non-existing user id. Typically a user is interacted with using CBs user table object, which won't do this since we just map to a empty Joomla user object. However the library API of Application::User directly calls CMS user object functions and will cause this if for example checking if a non-existing user is a moderator or checking for their ACL.