fix: #3593008 AccessPolicyProcessor::processAccessPolicies() creates...

   * {@inheritdoc}

   */

  public function processAccessPolicies(AccountInterface $account, string $scope = AccessPolicyInterface::SCOPE_DRUPAL): CalculatedPermissionsInterface {

    if (!\Fiber::getCurrent()) {

    // No Fiber isolation is needed when not in a Fiber, or when the requested

    // account is the current user (no account switch will occur in

    // doProcessAccessPolicies, so there is nothing to isolate).

    if (!\Fiber::getCurrent() || $account->id() === $this->currentUser->id()) {

      return $this->doProcessAccessPolicies($account, $scope);

    }

    // If running in a fiber, prevent the current user switch from escaping to

    // outside the fiber by resuming the fiber if it was suspended.

    // If running in a fiber and processing a different account, prevent the

    // account switch from escaping to outside the fiber by resuming the fiber

    // if it was suspended.

    $fiber = new \Fiber([$this, 'doProcessAccessPolicies']);

    $fiber->start($account, $scope);

    while (!$fiber->isTerminated()) {