<===> input.scss
@while {

}

<===> error
Error: Invalid CSS after "@while ": expected expression (e.g. 1px, bold), was "{"
        on line 1 of input.scss
  Use --trace for backtrace.

<===> error-dart-sass
Error: Expected expression.
  ,
1 | @while {
  |        ^
  '
  input.scss 1:8  root stylesheet