code: protected function getUser(): BackendUser
      {
          if (null === $this->tokenStorage) {
              throw new \RuntimeException('No token storage provided');
          }
  
          $token = $this->tokenStorage->getToken();
  
          if (null === $token) {
              throw new \RuntimeException('No token provided');
          }
  
          $user = $token->getUser();
  
          if (!$user instanceof BackendUser) {
              throw new \RuntimeException('The token does not contain a back end user object');
          }
  
          return $user;
      }
docs: Returns the back end user object.
  
  @throws \RuntimeException