Thank you playing my game, and for your kind comments. Congratulations for finding a bug, you described it very clearly so I was able replicated it myself and I know how to fix it! I don't know if I'm allowed to fix it during the jam, but thanks to your post other players will be warned.
Incidentally, you can use healing potions outside of combat using 1 Equipment -> 2 Use item -> 5 Drink Potion. In future I'll create a shortcut to that to make things easier.
Thanks again for the review!