class ErrorHandlerSubscriber

class ErrorHandlerSubscriber implements EventSubscriberInterface {
  
  /**
   * The current user.
   */
  protected AccountProxyInterface $account;
  
  /**
   * ErrorHandlerSubscriber constructor.
   *
   * @param \Drupal\Core\Session\AccountProxyInterface $account
   *   The current user.
   */
  public function __construct(AccountProxyInterface $account) {
    $this->account = $account;
  }
  
  /**
   * Register devel error handler.
   *
   * @param \Symfony\Component\HttpKernel\Event\RequestEvent|null $event
   *   The event to process.
   */
  public function registerErrorHandler(?RequestEvent $event = NULL) : void {
    if (!$this->account
      ->hasPermission('access devel information')) {
      return;
    }
    devel_set_handler(devel_get_handlers());
  }
  
  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents() : array {
    // Runs as soon as possible in the request but after
    // AuthenticationSubscriber (priority 300) because you need to access to
    // the current user for determine whether register the devel error handler
    // or not.
    $events[KernelEvents::REQUEST][] = [
      'registerErrorHandler',
      256,
    ];
    return $events;
  }

}