<===> input.scss
$foo: #{};

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

<===> error-dart-sass
Error: Expected expression.
  ,
1 | $foo: #{};
  |       ^^
  '
  input.scss 1:7  root stylesheet