Forge: 39.0.17
End Remastered: 5.0.1

Log: https://pastebin.com/39iQfhyy

I am assuming Forge changed something with mixins in their newer versions. Crashes on initial Minecraft launch.

At first look, it doesn't seem like a conflict with the forge launcher but rather a compatibility problem with electrodynamics' mixins

They did just release an update. I bumped the forge version at the same time i updated Electrodynamics so that makes sense. Would you prefer i reported over there?

It probably wouldn't be a bad idea to also report it on their repository but I'll try to figure out the root of the conflict

Reported the issue on their discord