When some mod combination causes loop in tech tree, the 248k's walk_techs algorithm in k2 overhaul mode causes factorio to hang without any error, because it never stops walking the tree

That sounds very worrying, do you have any mod I can use to replicate this bug?

I originally encountered this while trying to make 248k work with k2so.

To clarify, this is not a problem that occurs under normal conditions. Tech tree loops already make the Factorio error at loading, but the 248k's k2 overhaul mode trips up on it before the game has a chance to report it and causes a hang instead.

To easily replicate, create a sample mod that creates a tech loop

Here is a commit that makes the 248k load with k2so btw - https://github.com/Suplanker/248k-Redux/commit/6b490bcaac4a484fc0c3b0c34b9335aff9267cda

Tech loop was caused because k2so moved matter science to much later, making so fu_star_engine_tech tech could no longer depend on kr-matter-minerals-processing

Note that this patch provides only the basic experience, aka treating k2so as the base k2. It's playable, but doesn't interact with mechanics from space age. I have made more extensive k2so integration in a separate mod, and can try upstreaming it if there is an interest (haven't touched quality tho) or make a compat into a full separate mod

I added the commit so 248k can load with K2SO.

Regarding the tech loop, I believe you fixed the edge case, however, I still need to implement a failsafe in case something similar happens with another mod.