Repro dart-sass#1716

[Goodwine]

Repro sass/dart-sass#1716

Taking example - https://github.com/KaelWD/sass-forward-twice

1. Removed tab directory and @forward rules related to them (same error)
2. Renamed variables in use module with {...} to non-existing variables (same error)
3. Only used 1 valid variable (passed?)
4. Minimal repro attached (same error)

[skip dart-sass]
See sass/dart-sass#1739

Blocked on

• Note configurations are shared across all files in a module by instance given a uniquely-identifying opaque ID sass#3357