Created a test mixin for the demonstration and asked him the condition for the presence of $ arg:

@mixin test($arg) { @if($arg) { @error $arg; } }

If $ arg comes, then the check passes. I try to make a check on the negation of $ arg and get a syntax error:

 @mixin test($arg) { @if(!$arg) { @error $arg; } }

How to correctly check the negation in SASS (SCSS)?

    1 answer 1

    Decision:

     @mixin test($arg) { @if(not $arg) { @error $arg; } }