<===> input.scss
test {
  err: 2px % red;
}
<===> error
Error: Undefined operation: "2px mod red".
        on line 2:8 of input.scss
>>   err: 2px % red;
   -------^

<===> error-dart-sass
Error: Undefined operation "2px % red".
  ,
2 |   err: 2px % red;
  |        ^^^^^^^^^
  '
  input.scss 2:8  root stylesheet