Holding reference on phantom Object in node context of phridge

phridgePersistence.js

/**
 * THIS CODE DOES NOT WORK PROPERLY (yet). KEEP THAT IN MIND WHEN TRYING TO USE THIS!
 */

var phridge = require('phridge'); // https://www.npmjs.com/package/phridge
var through = require('through'); // https://www.npmjs.com/package/through
var S = require('string'); // https://www.npmjs.com/package/string
S.extendPrototype();
var Promise = require('promise'); // https://www.npmjs.com/package/promise

phridge.config.stdout = through(function(data){
  this.queue(data);
}, function(){
  this.queue(null);
});

// setup
phridge.config.stdout.on('data', function(data) {
  if (data.startsWith('myMsg:')) {
    // clean "myMsg:"
    data = data.substr(6);
    // clean trailing newline
    if (data[data.length-1] == '\n') {
      data = data.substr(0, data.length-1);
    }
    console.log(data);
  }
});

var phantomInstances = {};

function spawnPhantom (id) {
  return new Promise(function (resolve,reject) {
    phridge.spawn().then(function(phantom) {
      phantomInstances[id] = phantom; // <- important line, why does this not work properly?

      phantom.run(function () {
        this.page = webpage.create();
        this.page.onCallback = function(data) {
          console.log('myMsg:'+data);
        };
        // this.page.injectJs('simpleLogScript.js'); // if executed here, everything works like a charm.
      }).then(function () {
        console.log('Phantom instance ('+ id +') successfully spawned.');
        resolve();
      });
    });
  });
}

function injectScriptIntoPhantom (phantomId, scriptPath) {
  var myPhantom = phantomInstances[phantomId]; // <- important line, why does this not work properly?
  myPhantom.run(function() {
    this.page.injectJs(scriptPath);
  });
}

spawnPhantom('myId0').then(function () {
  injectScriptIntoPhantom('myId0', 'simpleLogScript.js'); // leads to rejection.
});

simpleLogScript.js

window.callPhantom('Hello World!');