StyleCollectionExtensions.SortBySpecificity does not account for null selector.

[The-Nutty]

Bug Report

I have observed instances where ICssStyleRule.Selector is null. This causes StyleCollectionExtensions.SortBySpecificity to throw a null reference exception.

Prerequisites

• Can you reproduce the problem in a MWE?
• Are you running the latest version of AngleSharp?
• Did you check the FAQs to see if that helps you?
• Are you reporting to the correct repository? (there are multiple AngleSharp libraries, e.g., AngleSharp.Css for CSS support)
• Did you perform a search in the issues?

For more information, see the CONTRIBUTING guide.

Possible Solution

I unfortunately dont have the raw HTML that caused this issue but i have confirmed the following change does fix the issue.

            rules.Where(m => m.Selector?.Match(element) ?? false).OrderBy(m => m.Selector.Specificity);

Would you accept a PR for this solution?

[FlorianRappl]

Yeah definitely!

Much appreciated 👍!

[FlorianRappl]

I already pushed it! Thanks for investigating this - indeed it was an issue and the fix works like a charme! 🍻

Landed in devel and the preview.

[The-Nutty]

Brilliant thanks.