Angular 2 / Typescript - TypeError: ClassName is not a constructor
<p>I am learning Angular 2 and I ran into this error while trying to create a service. I tried searching for a solution, but I cannot see my mistake.</p>

<p><strong>Error:</strong></p>

<pre><code>angular2-polyfills.js:1243 TypeError: Tweet is not a constructor
</code></pre>

<p><strong>Code:</strong></p>

<pre><code>export class TweetService{
    getTweets(){
        return tweets;
    }
}

let tweets = new Tweet("URL", "Author 1", "Handle 1", true, 50);

class Tweet {
    image: string;
    author: string;
    handle: string;
    status: "Lorem ipsum dolor sit amet.";
    isLiked: boolean;
    favorites: number;

    constructor(img, aut, hndl, ilkd, fav){
        img = this.image;
        aut = this.author;
        hndl = this.handle;
        ilkd = this.isLiked;
        fav = this.favorites;        
    }
}
</code></pre>