code: protected function onOAuthError($errorCode)
      {
          $errorCode = strlen($errorCode > 100) ? substr($errorCode, 0, 100) : $errorCode;
  
          $this->logger->notice(
              "OAuth2 error response: code {code}, provider {provider}",
              array(
                  "code" => $errorCode,
                  "provider" => get_class($this->provider),
              )
          );
  
          $this->session->addFlash("error", "The provider returned an error ($errorCode)");
          $this->picoAuth->redirectToLogin();
      }
docs: On an OAuth error
  
  @param string $errorCode