Fix bug when LOGGER is enabled, but LOGGERS is empty.
Fix bug when LOGGER is enabled, but LOGGERS is empty.

johnleeming/wekan,wekan/wekan,wekan/wekan,nztqa/wekan,johnleeming/wekan,wekan/wekan,nztqa/wekan,nztqa/wekan,wekan/wekan,GhassenRjab/wekan,GhassenRjab/wekan,johnleeming/wekan,libreboard/libreboard,wekan/wekan,GhassenRjab/wekan,johnleeming/wekan,libreboard/libreboard