It only crashes on client startup, not server side.

crash-2018-06-02_17.44.15-client.txt

Any luck with this build?

Still crashing.
crash-2018-06-02_22.17.09-client.txt

Weird... I can't recreate this error, neither client nor server. Which version of Forge are you using?

Forge 12.18.3.2511. It's all in the details, in the crash log.
I'll try with the recommended 12.18.3.2185 and let you know.

Don't worry, I was using that version too.

Does the mod run fine on its own? Just wondering if there's a particular nasty mod-mod interaction happening.

I think I identified Not Enough Items as the faulty mod, but another mod must be in conflict, as when I run NuclearCraft alone with NEI and it's dependencies (JEI, CodeChicken Core and codeChicken Lib), it doesn't crash.

Edit : I added Mekanism and it crashed.

crash-2018-06-03_16.26.39-client.txt

NuclearCraft with only Mekanism don't crash.

Aha - found the fix. Thanks for the help - will get it out shortly :)

You're welcome :)

Here we are - on CurseForge now :)