Prevent errors on rooms without usernames

packages/rocketchat-lib/server/functions/sendMessage.coffee

@@ -13,7 +13,11 @@ RocketChat.sendMessage = (user, message, room, upsert = false) ->
 	message.rid = room._id
 
 	if not room.usernames? || room.usernames.length is 0
-		room = RocketChat.models.Rooms.findOneById(room._id)
+		updated_room = RocketChat.models.Rooms.findOneById(room._id)
+		if updated_room?
+			room = updated_room
+		else
+			room.usernames = []
 
 	if message.parseUrls isnt false
 		if urls = message.msg.match /([A-Za-z]{3,9}):\/\/([-;:&=\+\$,\w]+@{1})?([-A-Za-z0-9\.]+)+:?(\d+)?((\/[-\+=!:~%\/\.@\,\w]*)?\??([-\+=&!:;%@\/\.\,\w]+)?(?:#([^\s\)]+))?)?/g