Since these error messages get printed in Terraform's output and we
encourage users to share them as part of bug reports, we should avoid
including sensitive information in them to reduce the risk of accidental
exposure.
The "config" package is no longer used and will be removed as part
of the 0.12 release cleanup. Since configschema is part of the
"new world" of configuration modelling, it makes more sense for
it to live as a subdirectory of the newer "configs" package.