ompugao/ctrlp-history — pull request #2 by pydave (2013-11-08 16:26:42+00:00)
Title: Display error when pattern is not found

Here's the suggestion I mentioned on 2b3aaa22d52ce75a675152d2f08cf0bd1b82dfb1.

I'm not sure if the t-mode is necessary. I haven't been able to get that error to fire, but I don't use vimgrep much.