This wedding or rather marriage is both symbolic and quite literal. After Esmeralda is executed and placed in a crypt, Quasimodo seeks in, lays down besides her, embraces her and dies next to her. So no actual fancy wedding takes place but the union is very clear and by god is it bittersweet.
Unlike the other weddings in Hunchback, this one seems like it genuinely came from a place of love even though Esmeralda is a non-player in this union, which I feel should bother me a little bit now that I think about it but it doesn’t really. The two skeletons wrapped in the embrace is so lyrical and tragic that it’s just so beautiful and the ending chapter gets me every single time I read it.
It’s also nice play on the whole “till death do we part” since death literally brought these two together.
I do wish more movies and adaptations would do this ending. We get it in the 1956 version and Notre Dame de Paris. Der Glockner hinted at it and I think, could be wrong, but English version of the Disney musical did it do, I think. I’m pretty Esmeralda dies at the end so why wouldn’t they do it. Then again the 77 version had Esmeralda die and didn’t do it but then again that’s the 77 version for you.