title: ContextErrorException in DebugClassLoader.php with ParameterBag class
body: <p>I'm using Symfony 2 and working with wamp server. After some time, i cannot access my pages anymore with that exception always showing, can't figuring why.
  Here's the full stack trace :</p>
  
  <pre><code>in DebugClassLoader.php line 203
  at DebugClassLoader-&gt;loadClass('Symfony\\Component\\HttpFoundation\\ParameterBag')
  at spl_autoload_call('Symfony\\Component\\HttpFoundation\\ParameterBag') in Request.php line 240
  at Request-&gt;initialize(array(), array(), array(), array(), array(), array([...]), null) in Request.php line 222
  at Request-&gt;__construct(array(), array(), array(), array(), array(), array([...]), null) in Request.php line 1964
  at Request::createRequestFromFactory(array(), array(), array(), array(), array(), array([...])) in Request.php line 281
  at Request::createFromGlobals() in app_dev.php line 27
  </code></pre>
  
  <p>It seems the "DebugClassLoader" class is using reflection to analyze what's wrong and it throws an exception when getting to the ParameterBag class. A var_dump() shows that ParameterBag is implementing \IteratorAggregate and \Countable as expected but also some random class "o" which i can't figure where it comes from.</p>
  
  <hr>
  
  <p>Prod environment will be an apache server running on a debian, maybe it will work on it but I'd better fix this on my current environment before going live.</p>
  
  <p>All the code I have which may deal with ParameterBag is something like that :</p>
  
  <pre><code>$session = $request-&gt;getSession();
  $session_id = $session-&gt;getId();
  $webclient = $em-&gt;getRepository('AppBundle\Entity\WebClient')
          -&gt;findOneBy(array("session_id" =&gt; $session_id));
  ...
  </code></pre>
  
  <hr>
  
  <p>Also note that clearing the cache does not fix this issue. (using php bin/console cache:clear [--env=dev])</p>
  
  <p>PS: restarting apache fixes it, but it shows again later</p>