gateways: null is not going to be a UUID either

ErrorException: Using null as an array offset is deprecated, use an empty string instead in /usr/local/opnsense/mvc/app/controllers/OPNsense/Routing/Api/SettingsController.php:162
Stack trace:

src/opnsense/mvc/app/controllers/OPNsense/Routing/Api/SettingsController.php

@@ -157,7 +157,7 @@ class SettingsController extends ApiMutableModelControllerBase
 
     public function getGatewayAction($uuid = null)
     {
-        if (!Type::isUUID($uuid)) {
+        if (!empty($uuid) && !Type::isUUID($uuid)) {
             /* uuid is likely a gateway name (legacy config) */
             $gateway = $this->getModel()->gatewaysIndexedByName(true, false, true)[$uuid] ?? [];
             if (!empty($gateway)) {