Expose Exception.toCssString() in the JS API

[zaydek]

Hi. Usually I build Sass using the CLI in watch mode, which has the nice characteristic that it compiles Sass, even when it's broken, and uses toCssString (internal Dart method) to serialize the Sass Exception as CSS using ::before so it's viewable in the browser.

I am triyng to compile Sass using the JavaScript API and I'm not seeing any way to get the error/exception formatted in this way, either through the Sass compile options or the SassException. I don't see anything here https://sass-lang.com/documentation/js-api/classes/exception/.

Is there a way developers whom use the JavaScript API can still compile Sass -- with errors -- and get the CSS string generated by this function? https://github.com/sass/dart-sass/blob/cd3b0cc1626f31a909d21fc87112d614cbb013e2/lib/src/exception.dart#L101

[nex3]

I think it's reasonable to expose a sass.Exception.toCssString() in the JS API. Since this is an API design feature, it should go in the Sass language repository.