Verify `derivatives` exist

[mgxd]

What happened?

Derivatives directories are checked in https://github.com/nipreps/nibabies/blob/2bd036d07904ed4a5c553971fc4ca48e4f45efa4/nibabies/workflows/base.py#L246but first used in

nibabies/nibabies/config.py

Line 493 in 2bd036d

derivatives=cls.derivatives or False,

We should immediately verify, warn + discard missing directories before initializing the layout

What command did you use?

n/a

What version of NiBabies are you using?

latest

Relevant log output

No response

Add any additional information or context about the problem here.

No response