Hi, thanks for your work.

Today i got the following error after updateing from 1.6.4 to 1.7.1 (still uses only factorio 1.1)

nearly 200 warning referenced to your mods cells, than an error:
31.449 Warning PrototypeList.cpp:130: No subgroup or bad subgroup for ic-container-plutonium-fuel-cell. Subgroup: ic-nuclear-plutonium.
31.449 Warning PrototypeList.cpp:130: No subgroup or bad subgroup for ic-container-breeder-fuel-cell. Subgroup: ic-nuclear-breeding.
31.449 Warning PrototypeList.cpp:130: No subgroup or bad subgroup for ic-container-MOX-fuel-cell. Subgroup: ic-nuclear-plutonium.
31.480 Error ModManager.cpp:1625: Error in assignID: item-subgroup with name 'ic-nuclear-plutonium' does not exist.

Source: ic-container-plutonium-fuel-cell (item).
32.221 Initial atlas bitmap size is 16384

this "ic-container" groups come from IntermodalContainers_2.0.8 mod
https://mods.factorio.com/mod/IntermodalContainers

Could you fix this, or it's an error in the other mod?

I think this is an error in Intermodal Containers, I will investigate further

Found the reason, it's because of how IntermodalContainers generated subgroups. Implemented a fix in Plutonium Energy 1.7.3, to not force adding an optional dependency for mod loading order in IntermodalContainers.
Plutonium Energy does some dynamic reorganization of the subgroups and items/recipes in the "second" mod data loading stage. A simple call to one of IC's lua files fixes it.

TL;DR: Fixed in upcoming 1.7.3

Update: I've contacted Xorimuth and we came to a better solution, Intermodal Containers will add a silent optional dependency for Plutonium energy and release an update for both 1.1 and 2.0. This will fix the issue for both versions. I'll revert the fix I've implemented in PE as it wouldn't be needed anymore.

thanks for your time, it's working again :)