code: public function onError($type, $message, $file = null, $line = null, $context = null)
      {
          // This will catch silenced @ function calls and keep them quiet.
          if (ini_get('error_reporting') == 0) {
              return true;
          }
  
          if (isset($this->fatalErrors[$type])) {
              throw new Exception($message);
          }
  
          if ($this->shouldNotifyError($type, $message, $file, $line, $context)) {
              // Make sure we pass in the current backtrace, minus this function call.
              $backtrace = debug_backtrace();
              array_shift($backtrace);
  
              $this->airbrakeClient->notifyOnError($message, $backtrace);
              return true;
          }
  
          return true;
      }
docs: Catches standard PHP style errors
  
  @throws Exception
  @see http://us3.php.net/manual/en/function.set-error-handler.php
  @param int $type
  @param string $message
  @param string $file
  @param string $line
  @param array $context
  @return bool