Add better error handling for the computer players

[Sothatsit]

Currently, if the computer errors while finding a move, it will never tell the user... This is bad UI.

We should at least notify the user! And better yet, we could try again just in case it works the second time. That way users wouldn't have to lose their games if an error occurs.

Luckily there have been no reports of errors in the computer analysis, but with the release of the extreme difficulty it has me a little bit worried.