SASS : (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px) isn't a valid CSS value

I am trying to process this on https://www.sassmeister.com/ the following file :

$grid-breakpoints: (
  xs: 0,
  sm: 576px,
  md: 768px,
  lg: 992px,
  xl: 1200px
) !default;
$utilities: () !default;

$utilities: map-merge(
  (
    "align": (
      property: vertical-align,
      class: align,
      values: baseline top middle bottom text-bottom text-top
    ),
    "float": (
      responsive: true,
      property: float,
      values: left right none
    )
), $utilities);


// Media of at least the minimum breakpoint width. No query for the smallest breakpoint.
// Makes the @content apply to the given breakpoint and wider.
@mixin media-breakpoint-up($name, $breakpoints: $grid-breakpoints) {
  $min: breakpoint-min($name, $breakpoints);
  @if $min {
    @media (min-width: $min) {
      @content;
    }
  } @else {
    @content;
  }
}


// Loop over each breakpoint
@each $breakpoint in map-keys($grid-breakpoints) {

  // Generate media query if needed
  @include media-breakpoint-up($breakpoint) {
    $infix: breakpoint-infix($breakpoint, $grid-breakpoints);

    // Loop over each utility property
    @each $key, $utility in $utilities {
      // The utility can be disabled with `false`, thus check if the utility is a map first
      // Only proceed if responsive media queries are enabled or if it's the base media query
      @if type-of($utility) == "map" and (map-get($utility, responsive) or $infix == "") {
        @include generate-utility($utility, $infix);
      }
    }
  }
}


// Print utilities
@media print {
  @each $key, $utility in $utilities {
    // The utility can be disabled with `false`, thus check if the utility is a map first
    // Then check if the utility needs print styles
    @if type-of($utility) == "map" and map-get($utility, print) == true {
      @include generate-utility($utility, "-print");
    }
  }
}

I have the following error :

(xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px) isn't a valid CSS value.

Any idea of what is wrong here ?