<===> input.scss
$a: 'foo';
$b: 'foo';
$map: (
  $a: 1,
  $b: 2
);

.foo {
  content: $a == $b;
  content: inspect($map);
}
<===> error
Error: Duplicate key "foo" in map ($a: 1, $b: 2).
        on line 3 of input.scss
  Use --trace for backtrace.

<===> error-dart-sass
Error: Duplicate key.
  ,
4 |   $a: 1,
  |   == first key
5 |   $b: 2
  |   ^^ second key
  '
  input.scss 5:3  root stylesheet