outputstream emits no data

i'm using the following code snippet with node v5.11.0, electron v1.4.13 and electron-microscope v2.0.0

I hope i'm not using it wrong. I'd be happy for a hint why the output$ stream is not logging anything.

var electron = require('electron')
var createMicroscope = require('electron-microscope')

electron.app.on('ready', function () {
  createMicroscope(function (err, scope) {
    if (err) throw err
    var url = 'http://google.de'
    var code = '(function () { return document.title || "m3h" })()'
    var microscope = scope.window.webContents
    function cb (result) { console.log(result) }

    scope.loadURL(url, function () {
      microscope.executeJavaScript(code, false, cb)

      var CODE = `function (send, done) {
        // put your custom code here
        // call 'send(data)' to write data to the stream
        // call 'done()' to end the stream
        // calling send is optional, but you must eventually call done to end the stream
        send(document.title)
        send('asdf')
        done()
      }`
      var output$ = scope.run(CODE)
      // @TODO: `output$` emits no data :/
      output$.on('data', function (data) { console.log('data: ',arguments) })
      output$.on('error', function (err) { console.error(err) })
    })
  })
})

Start by reproducing the provided Node, Electron, and electron-microscope snippet, especially the call to scope.run(CODE) and its output$ data listener. Compare the observed stream behavior with the expected document title and "asdf" values; done means determining why the stream emits no data and documenting or fixing that behavior.