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.
i've had the exact same issue on my mac, too, mojave 10.14.6. i tried it multiple times, and it always crashes whenever i leave the options menu. i'm no programmer, but as far as i can tell, it's just that it tries to save the options to a read-only file that should be read & write.
Do you have any idea when it'll be fixed? I lost three chapters worth of progress because of this.
and also, it wouldn't let me save. Just beeped at me. (I'm on a Mac too, Mojave 10.14.6)
