public override IGreenJsonSymbol VisitUndefinedValueSyntax(JsonUndefinedValueSyntax node, _void arg) => node.Green;
public override Style VisitUndefinedValueSyntax(JsonUndefinedValueSyntax node, SyntaxEditor <TSyntaxTree, IJsonSymbol, JsonErrorInfo> syntaxEditor) => syntaxEditor.Styles[undefinedValueStyleIndex];