I have absolutely no idea. I noticed it in the stacktrace before, but I couldn't really find anything about it.
That's fair, here's the repo on GitHub. Nothing special still, but I might have made a small mistake I haven't caught yet.
Not sure why my server will not start. Works fine locally. I did however copy and paste my mods from the local to the server, although it shouldn't be an issue since forge disables client side mods.