JavaScript - Instant command queue pattern

icq.js

var icqLibrary = icqLibrary || {};
icqLibrary.queue = icqLibrary.queue || [];

icqLibrary.queue.push(() => {
  console.log('Queue 1');
});
icqLibrary.queue.push(() => {
  console.log('Queue 2');
});

var icqLibrary = (function beautifulLibrary() {
  var icqLibraryApi = buildLibrary();
  return icqLibraryApi;

  function buildLibrary() {
    if (icqLibrary == null) {
      icqLibrary = {};
      switchQueueToInstantCommandExecution();
      
      return icqLibrary;
    }

    if (typeof icqLibrary == 'object' && Array.isArray(icqLibrary.queue)) {
      icqLibrary.queue.forEach((callback) => callback());
      switchQueueToInstantCommandExecution();
      
      return icqLibrary;
    }

    throw new Error('It seems that you are using my wonderful library in a wrong way.');
  }

  function switchQueueToInstantCommandExecution() {
    icqLibrary.queue = {};

    icqLibrary.queue.push = function (callback) {
      callback();
    };

    Object.freeze(icqLibrary);
  }
})();

icqLibrary.queue.push(() => {
  console.log('Instant queue');
});