This mod both warps you to the top of the world, y = 318 when you fall out of the world, and also prevents you from taking fatal fall damage, leaving you on a minimum of half a heart.
You can configure both from the Mods -> Configs screen or via the configs folder.
This is useful for skyblock, since constantly having to go get your stuff from the bottom of the world is annoying.
This is my first mod, if you run into any bugs or issues, please message me on discord: @shark_phoenix
License: CC0 (i.e. do whatever you want with it, equivalent to a public domain license)