fix: guard against NPE in eventFilteringUpdateAndCacheResource when patch target is deleted

Signed-off-by: David Sondermann <david.sondermann@hivemq.com>

Author: Donnerbart

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/event/source/informer/ManagedInformerEventSource.java

@@ -99,8 +99,12 @@ public R eventFilteringUpdateAndCacheResource(R resourceToUpdate, UnaryOperator<
     try {
       temporaryResourceCache.startEventFilteringModify(id);
       updatedResource = updateMethod.apply(resourceToUpdate);
-      log.debug("Resource update successful");
-      handleRecentResourceUpdate(id, updatedResource, resourceToUpdate);
+      if (updatedResource != null) {
+        log.debug("Resource update successful");
+        handleRecentResourceUpdate(id, updatedResource, resourceToUpdate);
+      } else {
+        log.debug("Skipping cache update since resource not exists");
+      }
       return updatedResource;
     } finally {
       var res =