The Razor Site Map template in 4.7 produces empty ul tags which will show as errors in html validators. The simple fix to prevent thsi for people who are fussy about validating their html (like me), is to add a check for there being items before outputting the ul tag, so the relevant ul section becomes:

   var items = node.Children.Where("Visible").Where("Level <= maxLevelForSitemap", values);
     if (items.Count() > 0) { 
       <ul>
                @foreach (var item in items) {
                    <li>
                     <a href="@item.Url">@item.Name</a>
                      @traverse(item)
                    </li>
                }
       </ul>
    }