ToME: the Tales of Maj'Eyal

I completed the quest without any issues, however as I was trying to gauge which of the 4 rewards to choose from, I tried to open my character dump, which resulted in the menu closing, meaning I didn't get the class unlock, and I didn't get any of the perk choices.Now I cannot open the tome to do this quest again in order to get the perks, it gives me an error saying "The book story is already done".

I can't tell if this will have repercussions in future playthroughs, so I thought I'd rather play it safe and report my issue here to clarify if this can be fixed, or at least, to know that in the future I won't be locked out of this quest line.

there is no unlock linked to this book.
you'll be able to read the book again on your next character.

how did you try to open char dump ?
because pressing "c" would select the third reward

I clicked my character portrait.

I didn't realize that this book doesn't unlock a class, my mistake.