Installed new mods (248k and related mods) to my game, went to load it, and received this error:

The mod Q's AI Core Mod (1.0.1) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event AICore::on_research_finished (ID 18)
AICore/control.lua:222: attempt to index field '?' (a nil value)
stack traceback:
AICore/control.lua:222: in function 'perform_tech_refresh'
AICore/control.lua:380: in function <AICore/control.lua:375>

Though, I dont know if its that important to fix, disabling AI Core, loading the save (which worked), saving, and then reenabling AI Core seems to work, and thats a decent enough workaround.

Can you send me a more detailed list of which mods you were using?

https://gist.github.com/nihilistzsche/ffb5234604b03345e653683932057dc5

It's a lot of mods, the error happened when I added 248k (and the associated mods) to an existing game. As I said in the second message though, disabling AI Core allowed the save to load, at which point I saved the game, and then reenabled AI Core, and it worked. As adding mods to an existing game is an ill-advised practice that I did anyway, I accept the risks of such an endeavor and disable/reenable is a decent enough workaround.