Work on ONMjs.observers.SelectedPathModelView...

... My problem with my Knockout template not resolving is that I had a typo in the declared function that retrieves the model view object on behalf of the window manager library.
Update to the window manager library to throw a reasonable error when...

... I forget that there's a difference between declaring a hosted model view window using MVVM.modelView (specifies a class that the window manager will new) and MVVM.fnModelView (specifies a function that the window manager will call to get an already existing instance of the model view to host in the window). I've added an exception throw to both cases in the window manager so that it's simpler to debug problems like the one I encountered last evening with a typo (and wrong model view declaration type).