Uncaught TypeError: Cannot read property 'users' of undefined
<p>I am using Gmail API to Send Email. but getting an error:</p>

<blockquote>
  <p>Uncaught TypeError: Cannot read property 'users' of undefined</p>
</blockquote>

<pre><code>&lt;script type="text/javascript"&gt;

    function sendMessage(email, callback) {
        // Web-safe base64 
        var base64EncodedEmail = btoa(email).replace(/\//g, '_').replace(/\+/g, '-');
        var request = gapi.client.gmail.users.messages.send({
            'userId': 'me',
            'message': {
                'raw': base64EncodedEmail
            }
        });
        request.execute(callback);
    }

    function send() {


        var to = 'vijay@itsabacus.com',
         subject = 'Hello World',

         content = 'send a Gmail.'
        var email = "From: 'me'\r\n" +
            "To:  " + to + "\r\n" +
            "Subject: " + subject + "\r\n" +
            "\r\n" +
            content;
            sendMessage(email, function () {
            console.log(arguments);
        });
    }
&lt;/script&gt;
</code></pre>