It's basically the same thing, though the circumstances are different. My guess is, based on the template name, that this is a custom alert but using a default content type. In that case, checking for the handler isn't going to work because obviously the post content type and the post alert handler will be available.
So I've added a bit of a sanity check, which actually runs in the controller (rather than the template) which involves filtering based on a new method called isAlertRenderable this ensures there's a handler (as we do now in the template) but also checks to see if the template actually exists. If it doesn't, we remove it from the list, and therefore no error when we try to render.
