While playing in a world created the previous preview today, the screen would go black and pressing any relative key combination wouldn't quit or escape the process. When running on macOS, Minecraft runs in a Java session that required me going into Terminal to force quit the process.
When this happened, I was in a boat on my way to find hidden treasure. When I rejoined the game, I started on the shore near where I hopped in the boat, and when I got close to where the game crashed before, it crashed a second time.
Following that crash, I force quit the Java process again, quit the launcher, and restarted my Mac. On restart, I launched Minecraft, loaded the world, and figured I'd head off in some other direction. About 10-15 minutes into playing, the same thing happened: The screen went black and I had to force quit the Java process in Terminal.
Please see the attached crashlog, which describes this as "Exception in server tick loop".
If this still occurs in the latest prerelease, could you please attach a copy of the world that can be used to recreate the crash?