Just in case this persists to when Raiguard updates the mod on here, the crash prints the message "Failed to load mods: Error in AssignID. item with name "rfp-antimatter-science-pack" does not exist. Source: rfp-antimatter-theory (technology)
Haven't looked inside K2 or this mod for the issue and I haven't tested K2 and/or this mod with default settings (it didn't crash on start for K2 1.1.6 with the same settings, so I don't know).
I wouldn't, after reading this, immediately go fix the issue (unless you feel you need to) until K2 here on the Mod Portal gets updated.
edit: To be more specific, whatever changes were made to version 1.2.3 (on github), that version is where nuclear fusion power (thus this mod too) shows the error message.
