Promises don't work about gtk-node HOT 9 CLOSED

import { App, Button } from '../../lib';

const app = new App({
  title: 'Node Gtk'
});
app.init((window) => {
  const button = new Button({
    name: 'Button 1'
  });
  button.attach(window);
  console.log('creating a set timeout');
  setTimeout(() => console.log('this will run after the application window closes'), 1000);
  app.render();
});

console.log('I will run after the application window is closed!');

creating a set timeout
// nothing will happen...
// now after the UI is closed by the user...
I will run after the application window is closed!
this will run 1 second after the application window closes

int init(GtkApplication *app) {
  g_signal_connect(app, "activate", G_CALLBACK(activate), NULL);
  int status = g_application_run(G_APPLICATION(app), 0, NULL);
  g_object_unref(app);
  return status;
}

/home/james/react-gtk3-project/node-gtk3/node_modules/ffi/lib/callback.js:18
        throw new Error(err)
        ^

Error: ffi fatal: callback has been garbage collected!
    at /home/james/react-gtk3-project/node-gtk3/node_modules/ffi/lib/callback.js:18:15
    at _combinedTickCallback (internal/process/next_tick.js:131:7)
    at process._tickDomainCallback (internal/process/next_tick.js:218:9)

init() {
    loop.startLoop();
    return new Promise((resolve, reject) => {
      // assign the ffi callback to 'this' so we retain a reference
      // after this.init() finishes. If we don't do this Node
      // will garbage collect it and we will get a segmentation
      // fault when C calls into it.
      this.onActivate = ffi.Callback('void', [type.GtkWidgetPtr], (windowPtr) => {
        this.window = new Window({ pointer: windowPtr });
        resolve(this.window);
      });
      app.register_on_activate(this.onActivate);

      // If we call app.init() then it blocks the main loop
      // forever and out program halts.
      // If we call app.init.async() then FFI will call the
      // foreign function in another thread (https://github.com/node-ffi/node-ffi/wiki/Node-FFI-Tutorial#async-library-calls)
      // My guess is that it will be scheduled on one of the
      // threads that LibUV controls for IO tasks.
      // This means we avoid blocking the event loop but this
      // results in a segmentation fault after some time and
      // I can't figure out why. My only guess is that it's a
      // multi-thread issue with GTK???
      app.init.async(this.pointer, () => null);
    });
  }