Mysterious Error in Client

[SlickEashy]

So, in my pursuit to update Kaos and Nilly's repo for the unobfuscated client I have ran into an error which puzzles me and is honestly quite frustrating. Here is the error:
I have no idea what is causing it and sometimes when I run it I get the error in a different place that is a little deeper in that same call in swiftsuspenders so I can't see the code there. I'm not necessarily sure anyone here can help me but it's worth a shot (yes, I already tried Google).

[CrazyJani]

I have it working but I never faced that error.

Edit: And yes, my class looks exactly the same as yours.