Since 1.14.0 (I'm not sure) my world has been crashing occasionally whenever I exit. The game saves the thumbnail for the world, and the world itself, but boots me from the game. World size is 250MB+.
Sometimes the world crashes while I'm playing, but if I reenter it doesn't crash when I leave again. In fact, I have two duped beds because it happened just after I slept, and the game saved the bed in my inventory as well as in the world.