ENHANCEMENT: Make SubscribeForm more robust, dealing with the special case when there is no newsletters can be subscribe to.
ENHANCEMENT: Make SubscribeForm more robust, dealing with the special case when there is no newsletters can be subscribe to.

guru-digital/silverstripe-newsletter,silverstripe-labs/silverstripe-newsletter,silverstripe-archive/silverstripe-newsletter,silverstripe-labs/silverstripe-newsletter,silverstripe-labs/silverstripe-newsletter,guru-digital/silverstripe-newsletter,silverstripe-archive/silverstripe-newsletter,guru-digital/silverstripe-newsletter