If you built a new filesystem, competent software engineers will heavily test the corner cases. What happens when the fs runs out of space? What happens when the metadata store runs out of space? etc.
The original article mentions bugs that are pretty obvious cases to test. What precisely happens when you have a sparsebundle that exceeds the storage capacity of the containing volume? A PM needs to define what should happen and an eng needs to test that it does.
It's inexcusable that things like this aren't tested and is an organizational failure. This isn't some complex interaction of earbuds with watch and a cloud system. This is a very testable filesystem.