Theme compile error

[paulpopus]

When trying to compile the theme there is a SASS error

Error in plugin "sass"
Message:
    node_modules/bootstrap/scss/_functions.scss
Error: argument `$string` of `str-index($string, $substring)` must be a string
        on line 58 of node_modules/bootstrap/scss/_functions.scss, in function `str-index`
        from line 58 of node_modules/bootstrap/scss/_functions.scss, in function `escape-svg`
        from line 319 of node_modules/bootstrap/scss/_navbar.scss
        from line 28 of assets/scss/lib/main.scss
>>   @if str-index($string, "data:image/svg+xml") {

   ------^

This is because we're overwriting a variable that needs to be a string.

This also means that the health check tests that run the compilation don't correctly handle errors.