twitter streaming api laravel 5

I've an programm that retreive favorites that belong to specific user. when I run php artisan twitter:listen-for-hash-tags commented function it's works in hashtag but when userStream I've an error [ErrorException] Undefined index: event

command code

<?php
 namespace App\Console\Commands;
 use Illuminate\Console\Command;
 use TwitterStreamingApi;
 class ListenForHashTags extends Command
{
/**
 * The name and signature of the console command.
 *
 * @var string
 */
protected $signature = 'twitter:listen-for-hash-tags';
/**
 * The console command description.
 *
 * @var string
 */
protected $description = 'Listen for hashtags being used on Twitter';
/**
 * Execute the console command.
 *
 * @return mixed
 */
public function handle()
{
    //TwitterStreamingApi::publicStream()
        //->whenHears('#laravel', function (array $tweet) {
         //  dump("{$tweet['user']['screen_name']} tweeted by {$tweet['text']}");
        //})
       // ->startListening();

    TwitterStreamingApi::userStream()
        ->onEvent(function(array $event) {
            if ($event['event'] === "favorite by {$event['source']['screen_name']}") {
                dump("Our tweet {$event['target_object']['text']} got favorited by {$event['source']['screen_name']}");
            }
        })
        ->startListening();
  }
}

via Chebli Mohamed