Affects Version/s: Minecraft 18w44a
Fix Version/s: None
When you die, the world completely disappears. You can fix this by quitting the world and joining back in, but this does sometimes cause chunk gen issues.
Steps to reproduce:
1. Create or enter a world.
2. Die (by any means, I have tested it in lava and by mobs as well as /kill).
3. (Optional) Exit and rejoin the world.
I have attached a video.