Using more recent versions of krastorio 2 (1.2.10+) causes a non-recoverable error with hazmat suits, should I manually download a previous version of krastorio, or replace hazmat suits with the fixed verison?
https://mods.factorio.com/mod/hazmat-suit-k2fix

I would manually download the previous version of Krastorio because the modpack hasn't been tested yet with the latest version. Also I would suggest not updating the mods at all once you've got a game going.

I will be fixing this in the future, of course.

I believe you will have to update to a different mod, according to the discussions on the Hazmat Suit mod's page... https://mods.factorio.com/mod/hazmat-suit/discussion/61d491365c248cf7d463507e

Solved, thanks for your report!