The player dies when their torso/head bars reach zero... but they can close the menu with ESC, and can regenerate while dead.

Install any version of Regen/First Aid
Die in a way that kills the player quickly (TNT, enchanted sword, etc)
Look at the twitchy broken animation

When the head or torso bars reach zero, regeneration process would begin.

Other Issue on different github

Thank you

Thanks for reporting! I'm not currently entirely sure what would cause this issue at the moment, I'll keep an eye on the other repo's issue and see what they have to say

This issue has not had activity in two months, is it still a problem? Let us know here asap! As seven days after this comment has been posted, the issue will be closed and marked as stale!

Please reopen this stalebot, I wanna use both firstaid and regeneration

I'll manually reopen