Error message when creating a users

@rsc When creating a user, the sign-up plugin throws this error:

see https://git.dmx.systems/dmx-plugins/dmx-sign-up/-/jobs/47592

{"error":"Creating custom user account failed, mailbox='testuser2@example.org', displayName='testuser2 Testuser'","cause":"java.lang.UnsupportedOperationException: Implement EmailTextProducer and set via SignupService::setEmailTextProducer"}

I guess this is because the plugin requires the UI plugin, or another text provider, right?