Hello,

I already resolved the issue by finding the class :P But I thought it worth telling you that your mod seems to use CofH Core as a dependency and it is not listed as such on your CurseForge. Might be worth adding it there, but the crash report is very clear so it is not really an issue for me. It might head off some other people coming to post bugs about it in the future though. Just for reference I am running Ex Astris without either EnderIO or Thermal Expansion. I am using Immersive Engineering and I added recipes for the blocks manually with minetweaker since they couldn't generate without either of the other mods installed. (Immersive doesn't require CofH core to run). I'll include a crash report just for completeness , but it is a clear case of Ex Astris calling ItemHelper from the cofh library and it not being present.

Crash Log:
http://pastebin.com/t3QwrHf8

Best,

Carbon