Chunks not loading on a server / Cannot invoke "cmq.a(int, int, int)" because "☃" is null

I'm hosting a minecraft server on my own device but every time I run the server and move around the console gives an error saying "main-worker-n-died". On my client I can see that some chunks aren't loading and in other chunks the player can't pick up items, mobs are standing still and entities in general are just stuck in place. Later, my server crashes.