Whenever I execute my program, I receive the following `TypeError`:

```
/home/Node-Project/node_modules/sentiment/lib/index.js:31
        afinn = Object.assign(afinn, inject);
                       ^
TypeError: Object function Object() { [native code] } has no method 'assign'
    at module.exports (/home/Node-Project/node_modules/sentiment/lib/index.js:31:24)
    at EventEmitter.<anonymous> (/home/Node-Project/twit4.js:17:9)
    at EventEmitter.emit (events.js:95:17)
    at EventEmitter.processTweet (/home/Node-Project/node_modules/ntwitter/lib/twitter.js:242:14)
    at EventEmitter.emit (events.js:95:17)
    at EventEmitter.receive (/home/Node-Project/node_modules/ntwitter/lib/parser.js:44:12)
    at IncomingMessage.<anonymous> (/home/Node-Project/node_modules/ntwitter/lib/twitter.js:258:16)
    at IncomingMessage.emit (events.js:95:17)
    at IncomingMessage.<anonymous> (_stream_readable.js:765:14)
    at IncomingMessage.emit (events.js:92:17)

```

I searched but I am unable to understand this error.

Do I have to install a special module?

Do I have to update Node or npm?

Is there an error in my program?

Here is my program:

```
var twitter = require('ntwitter');
var credentials = require('./credentials3.js');
var sentiment = require ('sentiment');

var twit = new twitter({
    consumer_key: credentials.consumer_key,
    consumer_secret: credentials.consumer_secret,
    access_token_key: credentials.access_token_key,
    access_token_secret: credentials.access_token_secret
});

twit.stream('statuses/filter',{ 'locations':'loc'}, 
function(stream) {
        stream.on('data', function(tweet) {
        var twitterSentiment, geoColor;
        sentiment(tweet.text, function (err, result) {
            twitterSentiment = result;
            if (result == 0) {
                geoColor = '#B5B5B5';
            } else if (result < 0) {
                geoColor = '#FC0828';
            } else {
                geoColor = '#00DE1E';
            } console.log(result);              
            });

        });
    });

```

Can someone please shed some light?