lib/upnp: Remove unnecessary error allocation

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3923

lib/upnp/upnp.go

@@ -226,7 +226,7 @@ func parseResponse(deviceType string, resp []byte) (IGD, error) {
 	}
 
 	deviceUUID := strings.TrimPrefix(strings.Split(deviceUSN, "::")[0], "uuid:")
-	matched, err := regexp.MatchString("[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}", deviceUUID)
+	matched, _ := regexp.MatchString("[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}", deviceUUID)
 	if !matched {
 		l.Infoln("Invalid IGD response: invalid device UUID", deviceUUID, "(continuing anyway)")
 	}