Now the crash occurs before I even reach the main menu! Once the white screen with the Mojang logo appears, the game crashes a few seconds afterward.
Yeah nothing has changed... game still crashes when generating, joining, or saving a world. Also crashes when going from handheld to TV mode in Switch
Exact same thing happens with me ( on the Switch too). The game would crash while loading a world, changing texture packs, changing skins, or at random times during the game.
The reason this happens is that as Mojang introduced, chunks unload(sort of) while looking away... They should have thought it through a bit more.
The game worked fine for a few minutes, but sadly, it soon began crashing again.