narrowed down error to call_hook('post_system')

I am not sure why this is happening. If I run my code with xdebug enabled, apache crashes at line 559 of codeigniter.php. Since this is the codeigniter code and not in phpStorm not Apache, I figured that this might be the best place to try to resolve my issue. 
$EXT->call_hook('post_system');
I don't know what this is for but next the code goes to 

public function call_hook($which = '')
{
  if ( ! $this->enabled OR ! isset($this->hooks[$which]))
  {
     return FALSE;
  }
Which returns FALSE. 

And then directly to _shutdown_handler() below. Since $last_error is null, the _error_handler() does not get called and the system crashes. Is this the way this is supposed to work?

   function _shutdown_handler()
  {
     $last_error = error_get_last();
     if (isset($last_error) &&
        ($last_error['type'] & (E_ERROR | E_PARSE | E_CORE_ERROR | E_CORE_WARNING | E_COMPILE_ERROR | E_COMPILE_WARNING)))
     {
        _error_handler($last_error['type'], $last_error['message'], $last_error['file'], $last_error['line']);
     }
  }
}