I'm getting this error at startup with the latest update.

Mod Loading Error

Mod loading failed: Error in assignID: item-subgroup with name 'armour-plating' does not exist.

Source: Light armor (item).

Mod to disable:

OCs_ammo_casting (0.9.1)

Additional description (1.2.2)

SetDefaultImportPlanet (1.0.0)

Thanks for the repot. I couldn't reproduce it yet, but maybe I already fixed it. If the error persist for the next hotfix, then I'll dig deeper into the two other mods. Maybe there's some unexpected things going on there.

Oh hey, I dealt with this issue a few months ago. One of your updates caused the issue mid playthrough so I reverted to an earlier version. Unfortunately I deleted the download so I can't remember the exact version, but I think it was 8.6 or 9.1 that I stuck with. I did just replicate the issue on vanilla by disabling the setting "activates armor tech tree". Without that your mod works in my 40+ modlist just fine.

Thanks for the report. First I have to find the source of that, but then I will work on a fix for that.

I found it, but as I am currently working on the big Factorio 2.1 update, I just give you the one line to fix. In the file OCs_ammo_casting/prototypes/item.lua
you should change this line:
if settings.startup["armour-plating"] then
to this here:
if settings.startup["armour-plating"].value then
If that works for you, great. If not, I will go the difficult way and create a real hotfix-update. The other option should be that you allow the armor plating, but don't use them.