When I start the game I keep getting this error. I deleted all the mods from the mods folder, but I still got the same error.

This is my first game I have finished. Before this I have played a couple of games, but never finished. I played for a while but then came to a point where I wasn't happy with how things were going or because I just sucked at playing haha. But things have changed and after watching some let's plays ...