2249 remove extraneous carat on second display of errors

Resolves BoT-Concern: https://code.google.com/p/otwarchive/issues/detail?id=2249

Noting here and on the issue that I mostly just took what Ariana had done previously, and just fiddled to get it to work. Wanted to give credit where it was due.
I guess `error_messages_for(prompt)` can be nil, even if the prompt isn't, probably when there are no errors.