Description:
------------
calling a class instance in isset causes an error 500

Test script:
---------------
<?php 
class MyClass {
  private $myobj;

  public function __construct() 
  {
    $this->myobj = 'Test OK';
  }

  public function getMyObject()
  {
    return $this->myobj;
  }
}

$instance = new MyClass();
echo empty($instance->getMyObject()) ? 'Empty value' : $instance->getMyObject();

//$myobj = $instance->getMyObject();    
//echo empty($myobj) ? 'Empty value' : $instance->getMyObject(); //Work correctly

?>

Expected result:
----------------
Test OK

Actual result:
--------------
500 Internal Server Error