mod_groups_internal: Fix traceback when room doesn't exist I'm not sure if it should even be included if it doesn't exist, but I'm not currently sure how this situation occurs, so I'm implementing the lightest possible fix for now.

-- this module is deprecated, log an error and load the superseding module instead
module:depends"smacks"

module:log("error", "mod_smacks_offline is deprecated! Just use mod_smacks!");