handle error when AppSets CRDs are missing

We see an error when trying to list AppSets when
AppSet CRDs are not installed hence ramen was in
an error state and unable to proceed as the namespace
was not returned. This is fixed by returning the default
namespace when AppSets CRDs are not found.

Bug: https://bugzilla.redhat.com/show_bug.cgi?id=2218181

Signed-off-by: rakeshgm <rakeshgm@redhat.com>

controllers/drplacementcontrol_controller.go

@@ -1707,6 +1707,12 @@ func getApplicationDestinationNamespace(
 ) (string, error) {
 	appSetList := argov1alpha1.ApplicationSetList{}
 	if err := client.List(context.TODO(), &appSetList); err != nil {
+		// If ApplicationSet CRD is not found in the API server,
+		// default to Subscription behavior, and return the placement namespace as the target VRG namespace
+		if meta.IsNoMatchError(err) {
+			return placement.GetNamespace(), nil
+		}
+
 		return "", fmt.Errorf("ApplicationSet list: %w", err)
 	}