After using Project E Integration v1.5.0 for quite some time now without issue I now get this crash when attempting to load my 1.12.2 world after updating to the recent PEI v2.0.0.

https://pastebin.com/fc6sn5CG

I am currently using forge 14.23.5.2823 in a probably excessive personal pack. I did attempt deleting the old PEI config and retrying without success. Reverting to v1.5.0 does indeed work as it used to. If there is any further information I could provide please let me know.

I noticed this after testing with Embers - Rekindled in a modpack, if you go into the config and switch off embers dawnstone anvil mapper the pack won't crash anymore.

plugins {
    embers: {
        B:enable_dawnstone_anvil_mapper=false
    }
}

For now however, I've added an TryCatch clause, so if any other Plugins/Mappers fail, the game shouldn't crash anymore. (Hopefully)

Interesting. I think I will try disabling the config for Embers Rekindled's Dawnstone Anvil mapper as you have suggested as well. I have encountered other issues with different mods before that mentioned that. Would toggling that option off have any negative effects that you know of?
I'll also give your new build a try before doing so to test things out as well. Thank you very much for the swift fix!

Disabling the mapper will only disable the EMC Conversion for the dawnstone anvil recipes. This means any recipe outputs using the dawnstone anvil won't get any automated EMC values

Understood. Thank you much for the help. I tested the PEI v2.0.1 release very briefly without toggling the Dawnstone Anvil mapper off and the world loads without issue now. All else appears to be working as intended though I obviously didn't dive too deeply into anything that quickly. I'll go ahead and close this now seeing as the issue is resolved. Thank you again for your efforts.