<===> input.scss
a {
  b: {
    @debug test;
    c: d;
  }
}

<===> error
Error: Illegal nesting: Only properties may be nested beneath properties.
        on line 3 of input.scss
  Use --trace for backtrace.

<===> output-dart-sass.css
a {
  b-c: d;
}

<===> warning-dart-sass
spec/libsass/debug-directive-nested/inline-dart-sass/input.scss:3 DEBUG: test