Ran into a really weird issue, and the logs aren't helping

I'm making a modpack, and as I was flying through the Nether, suddenly no more chunks were loading. I tried to close the game, but it wasn't even able to save the world, I had to force-close it.

I checked the logs, and normally I'm pretty good at finding the issue, but I don't see anything here that I could understand. Could someone please help me?

https://mclo.gs/6UYMgLj