nixos/radicale: assertion so that users set settings.auth.type explicitly

          are mutually exclusive.

        '';

      }

      {

        assertion = cfg.config != "" || (cfg.settings ? auth && cfg.settings.auth ? type);

        message = ''

          Radicale 3.5.0 changed the default value for `auth.type` from `none` to `denyall`.

          You probably don't want `denyall`, so please set this explicitly.

          https://github.com/Kozea/Radicale/blob/v3.5.0/CHANGELOG.md

        '';

      }

    ];

    warnings =