<===> input.scss
a {
    b {
        color: red;
    },
    c {
        color: blue;
    }
}
<===> error
Error: Invalid CSS after "": expected selector, was ","
        on line 4 of input.scss
  Use --trace for backtrace.

<===> error-dart-sass
Error: expected selector.
  ,
4 |     },
  |      ^
  '
  input.scss 4:6  root stylesheet

<===> error-libsass
Error: Invalid CSS after "    }": expected selector, was ","
        on line 4 of test.scss
>>     },