Error message
Deprecated function: Drupal\simplenews\Plugin\Field\FieldWidget\SubscriptionWidget::setAvailableNewsletterIds(): Implicitly marking parameter $newsletter_ids as nullable is deprecated, the explicit nullable type must be used instead in include() (line 571 of vendor/composer/ClassLoader.php).Deprecated function: Drupal\simplenews\SubscriberAccessControlHandler::checkFieldAccess(): Implicitly marking parameter $items as nullable is deprecated, the explicit nullable type must be used instead in include() (line 571 of vendor/composer/ClassLoader.php).
Deprecated function: Drupal\simplenews\Subscription\SubscriptionManager::subscribe(): Implicitly marking parameter $preferred_langcode as nullable is deprecated, the explicit nullable type must be used instead in include() (line 571 of vendor/composer/ClassLoader.php).
Deprecated function: Drupal\simplenews\Subscription\SubscriptionManagerInterface::subscribe(): Implicitly marking parameter $preferred_langcode as nullable is deprecated, the explicit nullable type must be used instead in include() (line 571 of vendor/composer/ClassLoader.php).
