Here is a latest.log of the crash : https://pastebin.com/fPqNQ4kq

I'm using:
MC 1.20.1
Forge 47.2.1
Shoppy-1.20.1-FORGE-1.1.0-all
EpheroLib-1.20.1-FORGE-1.0.0
EightsEconomyP-1.20-FORGE-1.1.2-all

Seems like there is a class missing or wrongly named

I see now you mention the depency OctoEconomyApi is required.
The question is: "Where do we find OctoEconomyApi "?

as far as I know, it's included in the mod

OctoEconomyApi is another repo hosted by the author of EightsEconomyP