A scss blurb generated from utopia.fyi doesn't generate custom sizes into the css.

This utopia.fyi link gives the following blurb that does not generate the expected --space-s-l variable.

@use 'node_modules/utopia-core-scss/src/utopia' as utopia;
  
/* @link https://utopia.fyi/space/calculator?c=400,16,1.2,1240,20,1.25,5,2,1512-450&s=0.75|0.5|0.25,1.5|2|3|4|6,s-l&g=s,m,xl,12 */

:root {
  @include utopia.generateSpaceScale((
    "minWidth": 400,
    "maxWidth": 1240,
    "minSize": 16,
    "maxSize": 20,
    "positiveSteps": (1.5, 2, 3, 4, 6),
    "negativeSteps": (0.75, 0.5, 0.25),
    "customSizes": ("s-l"),
    "prefix": "space-",
    "relativeTo": "viewport-width",
  ));
}

Work arounds

Looking at the code for calculateCustomPairs, it is expecting customSizes to be a list, but utopia.fyi outputs a single value in a parenthesis which is interpreted by sass as a string.

The user can force the configuration into a list in a couple of ways:

• Adding an additional custom size; and/or
• Manually changing the config to use a list by adding trailing comma within customSizes
  • i.e. "customSizes": ("s-l",),

Proposal 1

One fix could be to have calculateCustomPairs convert the single value to a list.

$pairs: ();
$customSizes: map.get($config, "customSizes");
@if (meta.type-of($customSizes) == "string") {
  $customSizes: ($customSizes,);
}
@if (meta.type-of($customSizes) != "list") {
  @return $pairs;
}
...

Proposal 2

One fix could be to have utopia.fyi output generate the customSizes config list to have a trailing comma.

I think if this approach is taken then calculateCustomPairs should generate an error if customSizes is not a list instead of silently ignoring it.