Fatal error: Call to a member function getItems() on null in

<?php            
      if ($storyFeed != false) {
	  $storyCount = count($storyFeed->getReel()->getItems());
	  for ($i=0; $i < $storyCount; $i++) {
      if ($storyFeed->getReel()->getItems()[$i]->getMediaType()==1) {
    echo "<div class='col-sm-12 col-md-6 col-lg-4 pptab'>
        <div class='pptabdiv'>
            <img src='".$storyFeed->getReel()->getItems()[$i]->getImageVersions2()->getCandidates()[0]->getUrl()."' width='480' height='850'>
        </div>
		<a href='".$storyFeed->getReel()->getItems()[$i]->getImageVersions2()->getCandidates()[0]->getUrl()."?dl=1'>Photo Download</a>
    </div>";
      } else {
        echo "<div class='col-sm-12 col-md-6 col-lg-4 pptab'>
        <div class='pptabdiv'>
            <video width='480' height='850' controls>
          <source src='".$storyFeed->getReel()->getItems()[$i]->getVideoVersions()[0]->getUrl()."' type='video/mp4'></video>
        </div>
		<a href='".$storyFeed->getReel()->getItems()[$i]->getVideoVersions()[0]->getUrl()."?dl=1'>Video Download</a>
    </div>";
      }
	  }} else {
		echo "YOK";
		
	  }
?>