How come so many dev teams are working with blindfolds on?

We have two projects that communicate using endpoints. One of them throws a parsing error with some data. Cool, just give the calling project some debug references and attach a debugger right?

Apparently not. I haven't figured out why we can't do that, it seems like the project only works using nuget references so we never get any debug info for the other project.

Asked around how we usually solve issues like this. The answer: "idk the codegen always works, so we never solve issues like this".

What.

It "always works". Except now it doesn't. And you've never tried debugging it? Instead just working with blindfolds on trying random shit until it does?

This is far from the first time I've heard this on a team. That and "we don't need error codes, if something goes wrong we have to fix it either way". I'm losing faith in the dev world...