Handle "Unknown message" module:"botstack:fallback"

Background...

fallback(message, senderID) { log.debug("Unknown message", { module: "botstack:fallback", senderId: senderID, message: message }); //fb.reply(fb.textMessage("Ops, internal short circuit... Shutting down... :("), senderID);* ----why does it happen that when this line is active it loops constantly?* };

This happens when Facebook sends messages that BotStackJS not yet able to handle correctly. Typically, this is a service message from facebook.