[TIMOB-24253] Android: onBackPressed() validate topWindow before hasProperty()

[garymathews]

• Prevent intermittent crash when topWindow is null

TEST CASE

var win = Titanium.UI.createWindow();
var imageView = Ti.UI.createImageView({
    height: Ti.UI.FILL,
    width: Ti.UI.FILL
});
 
var btn = Ti.UI.createButton({
    title: "Cam"
});
win.add(btn);
 
var overlay = Ti.UI.createView({});
var btn2 = Ti.UI.createButton({
    title: "take image"
});
btn2.addEventListener("click",function(e){
    Ti.Media.takePicture();
})
overlay.add(btn2)
 
btn.addEventListener("click", function(e) {
    console.log("----------------------------start camera------------------------");
    Titanium.Media.showCamera({
        overlay: overlay,
        success: function(event) {
              imageView.image = f.nativePath;
        },
        cancel: function() {     Ti.API.info('#### Camera Cancel');    },
        error: function(error) {},
        allowEditing: true
    });
})
win.add(imageView);
win.addEventListener("open", function() {
 
});
win.open();

JIRA Ticket

[lokeshchdhry]

FR passed.
Checked with the code above. Fix looks good. The app does not crash after we return back to the app from an androidback event.
Also, checked the original issue & works well.

Appc Studio : 4.8.1.201612050850
Mac OS Version : 10.12.2
Xcode Version : Xcode 8.2.1 Build version 8C1002
Appc CLI AND Appc NPM : {"NPM":"4.2.9-1","CLI":"6.1.0"}
Ti CLI : 5.0.11
Alloy : 1.9.5
Node : v4.6.0