I got a similar error when I hit "escape" on the options page.
and also, it wouldn't let me save. Just beeped at me. (I'm on a Mac too, Mojave 10.14.6)
Quick question, are you downloading and unzipping the files, or using the Itchio app?
Ahh, it was just downloading and unzipping. I just tried to test it via the app but using the app I get a different error on launch.
This error happens every time I try to launch the game. I uninstalled and reinstalled and still get the error when I launch the game.
I actually got that error at the same time, I assumed it happened because I was trying to save and the reaction was delayed, since it actually mentions a "save" folder.
Anyways, I just tested, and yeah, actually the error happens when exiting the options menu, not when trying to save.