Pop up a "not found" message for an unsuccessful search in a TaskBot

When I search for something that does not exist in my TaskBot, I'd like some kind of "not found" message to be popped up.

The reason I want this is that I think it may be faster for you to add this one message than to implement search functionality across multiple TaskBots, which is what I'm really trying to do (and which I think is low-priority to build, compared to the other things on the roadmap). If there is an error message to look for, then I think (hope?) I can create a TaskBot that searches across all my TaskBots.