It took me a while to figure this out, as I found no solutions online. Almost every forum I came across said there was no hope. Most tutorials on how to fix ticking entities focus on non-player entities or players that aren't the host. I was placing down a water block from little tiles and suddenly the game crashed as soon as I moved into it. Crash report showed ticking player entity, and every time I tried to rejoin it would crash with the same message. I couldn't kill myself without joining the world, and couldn't remove the blocks causing the issue, even by deleting the mod related to it. The solution: Create a forge server with the modded world, delete all player data, have a friend join the server and delete the blocks causing the issue, have them create a command block to instantly kill you as you join the server, and join.