To Reproduce
Attempted to open the mod config in-game. Immediately crashed to desktop, attempted again and it repeated.

Crash Report
crash-2020-10-08_00.27.26-client.txt

Additional context
I added a few extra fabric mods today, so it could be related to one of them, not sure.

Looks to be an issue with TooltipFix and AutoConfig; it's a new mod so it'll most likely be fixed soon.