improve: primary to secondary index edge case for dynamic mapper changes

Signed-off-by: Attila Mészáros <csviri@gmail.com>

Author: csviri

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

@@ -33,9 +33,13 @@ public synchronized void onDelete(R resource) {
     primaryResources.forEach(
         primaryResource -> {
           var secondaryResources = index.get(primaryResource);
-          secondaryResources.remove(ResourceID.fromResource(resource));
-          if (secondaryResources.isEmpty()) {
-            index.remove(primaryResource);
+          // this can be null in just very special cases, like when the secondaryToPrimaryMapper is
+          // changing dynamically
+          if (secondaryResources != null) {
+            secondaryResources.remove(ResourceID.fromResource(resource));
+            if (secondaryResources.isEmpty()) {
+              index.remove(primaryResource);
+            }
           }
         });
   }