title: Unidentified Index error only for some users
body: <p>Recently a strange bug has appeared and it happens only for some of the users. </p>
  
  <p>I have a payment gateway where the process will look like this: </p>
  
  <ol>
  <li>User enters his details and submits form. </li>
  <li>Some of the details are saved as SESSION data (email included) and from those session data, everything is recorded in a DB just fine. </li>
  <li>User is redirected to safe third party payment gateway. (Offsite)</li>
  <li>If payment successfull user is redirected back to my server to record the transaction in my database.</li>
  </ol>
  
  <p>This is where it gets funky.</p>
  
  <p>On return, only a few of the users will have lost their SESSION data, because when I run this: </p>
  
  <pre><code>$all = ChargeBee_Customer::all(array(
       "email[is]" =&gt; $_SESSION["email"],
  ));
  </code></pre>
  
  <p>I will get a:</p>
  
  <p>PHP Notice:  Undefined index: email in "Dir to file" on line 299</p>
  
  <p>The code part above is Line 298,299,300</p>
  
  <p>Not sure what could be the bug here, since this happens only to some of the users. </p>