this works even without resizing: MC-30646
It can be extended:
Create an (ingame) undeletable but unplayable hardcore world.
Environment:
new hardcore world (2 times)
Reproduction:
create hardcore world
die (I falled from a high place)
resize the window (I max. it)
You wont be able to do anything (see the original bug) now so:
close the window with "X"
restart minecraft
load the world
You will see: "Game over" and "Delete world"
klick "Delete world"
Effect: You will get kicked to the main menu, but the world wont be deleted!
You just can "play" it again: You will see the "Game over" again and again.
You can delete it from the main menu, sure, but not with dieing in the hardcore world
.
See my issue MC-85062
It's obviously a singleplayer world.
I didn't change anything in the mincraft data.
You are right. This works even without the resize.