title: Firebase Phone Auth - RecaptchaVerifier Type Error
body: <p>I am trying to implement Firebase Phone Number Authentication as described <a href="https://firebase.google.com/docs/auth/web/phone-auth" rel="nofollow noreferrer">Here</a></p>
  
  <p>However when I try try and create the RecaptchaVerifier object as per the docs:</p>
  
  <pre><code>window.recaptchaVerifier = new firebase.auth.RecaptchaVerifier('recaptcha-container');
  </code></pre>
  
  <p>I get the following error:</p>
  
  <blockquote>
    <p><strong><em>Uncaught TypeError:</strong> Cannot read property 'bind' of undefined
        at new FirebaseAppImpl.(anonymous function)</em></p>
  </blockquote>
  
  <p>which seems to be from this line of code in the Firebase SDK:</p>
  
  <pre><code> var serviceFxn = this._getService.bind(this, name);
  </code></pre>
  
  <p>Has anyone successfully implemented this?</p>