// Same as GetSelfOrNewNavigator, but also verifies that the result is parked on an element node.
private static XPathNavigator GetSelfOrNewElementNavigator(this IXPathNavigable element, string paramName = "element")
{
var nav = element.GetSelfOrNewNavigator(paramName);
if (nav.NodeType != XPathNodeType.Element)
{
throw new ArgumentException("Operation not valid on non-element node (" + nav.NodeType.ToString() + ")", paramName);
}
return(nav);
}