Update report.php (OpenMage#1588)

This should improve OpenMage#1581

If checks that parameter $_GET['id'] is passed (it's then casted to int by processor.php) but ONLY if the report.php script is called directly.
This first part of the check is necessary because report.php is included in Mage::printException()

Author: fballiano

errors/report.php

@@ -24,6 +24,8 @@
  * @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
  */
 
+if ($_SERVER['SCRIPT_FILENAME'] == __FILE__ && (!isset($_GET['id']) || strlen($_GET['id']) == 0)) die("Missing parameter: id");
+
 require_once 'processor.php';
 
 $processor = new Error_Processor();