Issue #3456871 by Tim Bozeman: Support NULL services

core/lib/Drupal/Component/DependencyInjection/ReverseContainer.php

@@ -70,7 +70,7 @@ public function getId(object $service): ?string {
    */
   public function recordContainer(): void {
     $service_recorder = \Closure::bind(function () : array {
-      return $this->services;
+      return array_filter($this->services);
     }, $this->serviceContainer, $this->serviceContainer);
     self::$recordedServices = array_merge(self::$recordedServices, array_flip(array_map([$this, 'generateServiceIdHash'], $service_recorder())));
   }