After dying in Hardcore mode, the game asks you whether to spectate or to delete the world.
Selecting the 'Delete world' option causes the game to return to the main menu without unloading the world. The internal server keeps running and the player is still connected to it. The main menu's background is a white screen.
Attempting to load a singleplayer world results in a black screen.
Environment
Java Virtual Machine
OpenJDK Java 14 (Early Access) Build 5 (HotSpot VM).
Also tested under OpenJDK Java 8 Update 222 (HotSpot VM).
System
CPU: Intel(R) Core(TM) i3-2120 @ 3.30 GHz.
RAM: 2 GB DDR3 (1333 MHz).
GPU: Intel(R) HD Graphics 2000.
Display: 1280x1024 VGA @ 75 Hz.
Operating system
Arch Linux
Kernel: Linux 5.1.18-1-clear
Drivers:
"intel" module for X.Org display.
Mesa 19.2.0-devel (git-f239e22813).
Thanks for the report; however this is a duplicate of MC-148865.