Is your feature request related to a problem?

Currently, if setup-meta-modules doesn't match any compilers, it will quietly fail (no .lua files generated) without an error.

Describe the solution you'd like

There are a few ways to handle this, but probably the easiest and most foolproof would be a check at the very end that ensures that at least one directory starting with 'stack-' exists under $SPACK_ENV/modules/. And/or put a counter next to the modulefile write functions and assert that we hit that code at least once.