Fixes a bug with error reporting in the RTT API endpoint

src/service/clmcservice/graphapi/views.py

@@ -194,13 +194,15 @@ class GraphAPI(object):
                 log.error("Unexpected error occurred while executing RTT cypher query for graph with UUID {0} - {1}".format(graph_id, e))
                 raise HTTPBadRequest("The Neo4j cypher query didn't return a valid result for the temporal graph with ID {0}".format(graph_id))
 
-        sf_node = graph.match(nodes=(None, endpoint_node), r_type="realisedBy").first().start_node
+        sf_edge = graph.match(nodes=(None, endpoint_node), r_type="realisedBy").first()
+        sf_node = sf_edge.start_node if sf_edge is not None else None
         if sf_node is None:
             msg = "No service function found associated with endpoint {0}".format(endpoint_node["name"])
             log.error("Unexpected error: {0}".format(msg))
             raise HTTPBadRequest(msg)
 
-        sf_package_node = graph.match(nodes=(sf_node, None), r_type="instanceOf").first().end_node
+        sf_package_edge = graph.match(nodes=(sf_node, None), r_type="instanceOf").first()
+        sf_package_node = sf_package_edge.end_node if sf_package_edge is not None else None
         if sf_package_node is None:
             msg = "No service function package found associated with service function {0}".format(sf_node["name"])
             log.error("Unexpected error: {0}".format(msg))