Squiggle display of errors for switch expression

Hi, We are using the CSharpSyntaxLanguage provided and having similar code snippets shown below. We've then encountered an issue that squiggle display of errors appear on the line for the default. If I replace the throw exception part with some string value, it would then happy. I believe that syntax is part of C# 8.0, which should be fully supported by the SyntaxEditor, do I miss anything or maybe there's some extra setup required?

    int testBit;
    string result = testBit switch
    {
        0 => "P",
        1 => "F",
        _ => throw new Exception()
    };