Game crashes when creating any world

Bog-standard computer, all vanilla. Starts up as normal.

I make a new world. It shows the animation from 0% to 100, and "Joining world"... then

"An unexpected error has occurred and the game has crashed." etc.

Nothing in the "crash-reports" folder.

Launcher log attached.

1.14.4 works fine.

I am not a moron, I've played MC for about 8 years.

Help?