Yep, that will happen!
We've set those links up to 'Search' the Traffic Codex site for any available Promo Codes for that domain. If there are Promo Codes available, you'll get a page linking to them. If there's nothing in the Traffic Codex database you'll get an error message.
We've deliberately left our links to those sites in place, just in case someone adds a Promo Code in the future. So if you get an error, just close the window and move on...