Fix 1472 - Error executing upgrade action over K8S NS

Change-Id: Ibc9cb5e12d90f5582f49d99bcee002e2813dd9eb
Signed-off-by: limon <alimonj@indra.es>
diff --git a/osm_nbi/instance_topics.py b/osm_nbi/instance_topics.py
index cae9f54..bf0e3a9 100644
--- a/osm_nbi/instance_topics.py
+++ b/osm_nbi/instance_topics.py
@@ -772,18 +772,20 @@
                 descriptor_configuration = utils.find_in_list(
                     configs,
                     lambda config: config["id"] == indata["vdu_id"]
-                ).get("config-primitive")
+                )
             elif indata.get("kdu_name"):
                 self._check_valid_kdu(vnfd, indata["kdu_name"])
                 descriptor_configuration = utils.find_in_list(
                     configs,
                     lambda config: config["id"] == indata.get("kdu_name")
-                ).get("config-primitive")
+                )
             else:
                 descriptor_configuration = utils.find_in_list(
                     configs,
                     lambda config: config["id"] == vnfd["id"]
-                ).get("config-primitive")
+                )
+            if descriptor_configuration is not None:
+                descriptor_configuration = descriptor_configuration.get("config-primitive")
         else:  # use a NSD
             descriptor_configuration = nsd.get("ns-configuration", {}).get("config-primitive")