I am experiencing the exact same issue. Also of note, earlier in the questline when I attempted to grab her soul jar and place it in my bag, the interaction closed and nothing happened. I had to reload a recent save to actually get the soul jar. Reloading at the Sanctuary does not fix the Gratiana dialogue crash. Smashing the soul jar also doesn't do anything (release her soul with her saying she isn't done yet) but remove the jar from inventory.
