sdsv3: Don't log error when connection closes

If we receive a nil error on the errch it means that the connection
has been closed cleanly. We shouldn't log an error in that case.

Signed-off-by: Sorin Dumitru <sdumitru@bloomberg.net>

pkg/agent/endpoints/sdsv3/handler.go

@@ -171,7 +171,9 @@ func (h *Handler) StreamSecrets(stream secret_v3.SecretDiscoveryService_StreamSe
 				continue
 			}
 		case err := <-errch:
-			log.WithError(err).Error("Received error from stream secrets server")
+			if err != nil {
+				log.WithError(err).Error("Received error from stream secrets server")
+			}
 			return err
 		}