SNIClient: log exceptions and keep task alive

[beauxq]

What is this fixing or adding?

I think this is a better solution to this problem: https://github.com/ArchipelagoMW/Archipelago/pull/3404

To the user it displays the "An error occurred..." message. In the text file log, it gives the full stack trace. It allows the game_watcher task to continue.

How was this tested?

In snes_read I put:

if random() < 0.05:
    return None

and in Super Metroid's client I un-handled the None value of the first snes_read so it would throw an exception.

I saw the "An error occurred..." message in the client window, and I looked in the text log and saw full stack trace, and the client was able to continue playing.