TypeError: Value undefined does not allow function calls

[makadodo]

I'm getting this error whenever a listener is attempting to call a
callback function.

In the demo code, accordion.js, I modified makeSimple

makeSimple: function(){
var utilwin = new dair.Window({
size:{
t:100, l:300, w:300, h:400
},
href: "app:/html/notes.html",
});
utilwin.addEventListener(air.Event.CLOSING, onClosing);
simple = getWindow().inApp.addWindow(utilwin)
},
onClosing: function(closingEvent) {
console.debug((closingEvent + " test")
},


The objective is to have the child window close when main window is
close by licening to CLOSING event.

Despite that Introspector is reporting this error, the child window
will get close when the main window is close.

I'm seeing the same error when trying to port an existing dojo app to
D'Air.
In one of the widget, it has this

dojo.subscribe("myapp.filteringSelect.selected", this,
"_updateStoreForSelect");

Thank you