I don't know what happened or how I died, because the screen automatically showed up when I tried to play. It is stuck on the death screen in my single-player creative world, and the respawn button responds when clicked (makes the sound, gets grayed out) but does nothing. When I click the title screen button, it gets stuck on the 'Saving world' screen and cannot be closed from either the window itself or the task manager. The only way to close it is by restarting.
Launcher log: https://paste.ubuntu.com/p/zhddMPHYqN/