<===> input.scss
.test {
    a: a#{b//}c;
}

<===> error
Error: Invalid CSS after "}": expected ";", was ""
        on line 4 of input.scss
  Use --trace for backtrace.

<===> error-libsass
Error: Invalid CSS after "    a: a#{b": expected expression (e.g. 1px, bold), was "//}c;"
        on line 2:10 of input.scss
>>   a: a#{b//}c;
   ---------^

<===> error-dart-sass
Error: expected "}".
  ,
3 | }
  |  ^
  '
  input.scss 3:2  root stylesheet