[TIMOB-24284] Hyperloop: iOS - Hyperloop.defineClass fails when subclassing NSObject

Hyperloop.defineClass() method is preventing my app from building with an uncaught exception during build/deploy to device or simulator. In the log output I get:

[INFO]  Processing JavaScript files
An uncaught exception was thrown!
Hyperloop.defineClass must return a class definition into a variable

I just did a File -> New Mobile App in Appcelerator Studio and added 1 line to "index.js"

var myFoo = Hyperloop.defineClass('MyFoo', 'NSObject');

function doClick(e) {
    alert($.label.text);
}

$.index.open();

I also have

<use-jscore-framework>true</use-jscore-framework>

added in my tiapp.xml no other changes from the default "new project" template in Appc Studio.