Thanks for submitting the traceback! If you don't mind, what platform does this happen on? I was fairly certain I've fixed this error since the early access build release, but looks like I could've been wrong.
In the meantime, please access the cheat menu by going to your room in the mansion and clicking on "Write in the journal". From there, type in "clearinventory" to remove the corrupted item record, then "giveitem picklepotion" to give yourself the potion again. That should unblock you so you can continue playing. Sorry for the issue!
Thank you so much! I'm glad you enjoyed the game, and I hope the upcoming updates meet your expectations!