I have a navigation helper which checks the id of the current page and compares it to the navigation item being rendered and then gives a class of selected if it returns true.

for example

@helper SelectedStyle(dynamic page) {
    
if (CurrentPage.Id == page.Id || CurrentPage.AncestorOrSelf(2).Id == page.Id || CurrentPage.AncestorOrSelf(3).Id == page.Id)  
  {
    @Html.Raw("class=\"selected\"");
  }
}

The trouble is it errors on top level nodes which dont have children that go three levels deep.

the error is:

Cannot perform runtime binding on a null reference

because there is no 3rd level on that particular node.

how do I get it to fail silently?
I've tried all sorts like

if(String.IsNullOrEmpty(CurrentPage.AncestorOrSelf(3).Id) == false)

and

if(CurrentPage.AncestorOrSelf(3).Id = null)

but everything I try seems to fall flat.

what is the correct way to see if CurrentPage.AncestorOrSelf(3) returns null or not?

- Tim