React map function doesn't run

i'm trying to show some posts from firebase, but the map() function is not running and the array is not null.

render() {

    console.log('posts', this.state.posts);

    const posts = this.state.posts.map((value, index) => (

        console.log('author', value.author)
        //<Post author="{value.author}" />

    ));

    return (

        <div className="container">
           <div className="col-md-4 col-md-offset-4 mt-md">
                {posts}
           </div>
        </div>
    );
}

Here is the full code -> http://ift.tt/2uNMJOk .

Thanks!