Fixed:
  - Fatal error in sign_for_acknowledgement_get_roles() when config references a
    role that no longer exists ("label() on null"); missing roles are skipped.
  - Fatal error in the table when a configured custom field does not exist on the
    site; the field key is used as a fallback label.
  - Fatal error in NodeTypeAccessCheck when the route node id does not resolve to
    an existing node; access is now denied cleanly.
  - PHP 8.4 compatibility: explicit nullable parameters in the database/email
    services and in the role/user allowed-values callbacks.