Sculpin error: Didn't find at least one of this type

While building this Website I encountered an issue which was rather trivial but that took a while too uncover.
Symptoms
My Sculpin website was perfect when I builded it in dev mode. But everytime I tried to build the prod environnement, I would see this message in the console output.
Didnt find at least one of this type : posts
It was rather confusing for me as I added that error message to be able to debug some more complex website that I built with Sculpin. Namely a webiste that had multiple content types added to it.
But it isn't the case for this blog (yet).
It happears that I hit a rather unusual corner case. As I built this website starting from the official sculpin blog skeleton, I kept most of the frontmatter from demo posts. In the demo posts frontmatter, I missed the option that indicated that the content was a draft.
And all my trouble came from there.
Fix
Simply setting that option to false or removing it did solve my problem.
draft: false