init = () => {
  // Initialize the command queue in case analytics.js hasn't loaded yet.
  window.ga = window.ga || ((...args) => (ga.q = ga.q || []).push(args));

  createTracker();
  trackErrors();
  trackCustomDimensions();
  sendInitialPageview();
  sendNavigationTimingMetrics();
}
Initializes all the analytics setup. Creates trackers and sets initial
values on the trackers.