As something that I noticed while testing this bug, you CAN escape this without relogging.
If you teleport enough times, like with this: /tp @p @e[sort=random,limit=1]
Then you aren't stuck.
However, you will then end up in a situation like
where you only see parts loaded. I hope this helps in identifying things.
Edit: It does eventually fix itself after 10 more minutes of testing. I eventually teleported to spawn and everything was loaded properly.
I can confirm with the above. Having a profile that sets custom resolution will have the snapshot instantly crash. And only for the snapshots of 1.13. 1.12 and the like are unaffected so this was recently introduced.
Guess for now the solution is to turn it off. (hopefully fixed soon!)
Happy it wasn't related to my recent moving of files around. (since snapshots are stored in a different area than release)
This seems to affect all dimensions, even custom ones via data packs.
It worked in previous snapshot 25w37a. As of the prerelease, mobs do not spawn in any dimension but the overworld.