I'd love it if there was an undo button after an action.

I accidentally marked my book as finished while trying to update the page I was at and I had to delete the book a re-add to my "currently reading" to bring it back. However by deleting it, it removed all the progress I made in my activity calendar. There is no way to get that back unfortunately (as far as I know)

If there had been an undo button, my problem would have easily be solved!