Return type of ContaoFramework::getContainer() should either be compatible with Symfony Component DependencyInjection ContainerInterface
Problem Description When a Contao 4.9 LTS site is executed under PHP 8.1+ the console and web logs contain deprecation notices such as: Return type of Contao\CoreBundle\Framework\ContaoFramework::getContainer() should either be compatible with Symfony\Component\DependencyInjection\ContainerInterface::getContainer(): ?Psr\Container\ContainerInterface, or the