title: Magento Payu error
body: <p>We are using <code>pay u</code> for our magento site, after installing <code>pay u</code> when user redirects to <code>pay u</code> site and click on browser back button without dong payment magento shows error like </p>
  
  <pre><code> Fatal error: Call to a member function getMethodInstance() on a non-object in /app/code/core/Mage/Payment/Model/Observer.php on line 46  
  </code></pre>
  
  <p>but order is already placed with status as 'processing' and after clicking on back button it goes to checkout page showing products in shopping cart.  </p>
  
  <p>That menas order is placed and shopping cart is not empty After resolving that issue of <code>observer.php</code> magento places order twice once with 'processing' status and one empty order.  Kindly help with this.  Thanks </p>