Currently, we allow hiding/showing of Template Roots via the Navigator. However, setting to 'Hidden' immediately produces a XAML error in Studio.

This is a very minor one because it seems to have no ill-effect and doesn't even seem to produce an error in VSCode when inspected further.

However, with that said, we likely shouldn't offer an option in Studio that instantly produces the red 'XAML Errror" 'X' notifiction.

(Also: This error persists on the Page even with the Element removed from the Stage, the only way to clear it is to set the Root to 'Visible' or to delete the Template from the Projec'ts Resources)

Repro Steps:

1) Create a Project containing a MainPage.xaml

2) Introduce a Button to the Page, and create a Template of it.
This will open the Template in the Template Dummy Editor.

3) Hover over the '[ControlTemplate] "Button" layer in the Navigator, and click on the Eye Icon to hide it.

Observe how a XAML 'X' error is immediately produced in the lower right of the Stage.

Expected Results:
a) Remove the Show/Hide Eye Icon from Root Elements to remove the possibility for the error to occur in the first place
or
b) We ensure that if this operation is indeed non-problematic insofar as the XAML is concerned, that is doesn't produce a XAML Error Warning.