Is it too much for a children's book to end on a tragedy?
Some context for this question: I'm writing and illustrating a very short book aimed at children aged 8-10 for an assignment at my uni. There are almost no requirements other than the story should have a moral lesson component.
I opted to go for a simple story about a knight obsessed with slaying a vile dragon, only for the dragon to turn out small and harmless. But, due to his paranoia and fear of the unknown, the knight attacks and endangers the innocent creature.
The ending here is what's giving me trouble. I feel like the story ending with the dragon getting killed might be too dark for a children's book. On the other hand, I can't help but feel like a happy ending undermines the moral of the story and the takeaway I want for readers to get — hating and fearing something/someone you're unfamiliar with might bring harm to truly innocent souls. I'm afraid shying away from the consequences of this issue would lessen the impact of the message.
So, those who write children's books or writers who are also parents, what is your opinion on tragedy in stories aimed at children? Would it be traumatizing? Or would the story just be more memorable this way?