wasm: Exit app with async main() results on runtime error

Hi,

According to: https://doc.qt.io/qt-6/wasm.html#application-startup-and-the-event-loop

Particulary this sentence: "Application code then omits making the exec() call, and can shut down Qt cleanly by deleting the top-level window and application objects."

We can have an application with a async main function and then, when the main window is closed, we delete all application objects and the application should exit fine

I cannot make it to work completly fine with the linked code.

The app is simple:

• have a main class, subclassing QGuiApplication, creating the QQmlApplicationEngine, loading the qml module
• have a signal in qml when the button is pushed
• c++ should delete the qml root object
• when informed of qml root object deletion, require to delete the main class, thus, cleaning all remaining objects

The application do exit, but with an error, on firefox:

And on chrome: