Quest: https://en.uesp.net/wiki/Tamriel_Rebuilt:Yamandalkal_(quest)

Relevant dialogue topic: Yamandalkal

I killed Xivilai Tatho before I even started this quest. So in my dialogue with Gindaman I got the quest, then clicked the "Yamandalkal" topic again, which already triggered his disappointment and finished the quest, then I clicked it again, which made him say that the business is concluded -- but that added one more journal entry: that he was glad. See screenshots attached. I think there is no need to set the quest stage to 100 when the condition for that dialogue is already ">= 100" (300 in my case)