net/zerotier: Prevent invalid 'local.conf' on initial save.

There is potential for an invalid local.conf to be written out during first
save. Whilst it doesn't stop Zerotier from starting, it does cause it to
return a 1 as an error code, thus fooling configd that the service has failed
to start. Adding in a default '{}' resolves this issue.

-=david=-

net/zerotier/src/opnsense/mvc/app/controllers/OPNsense/Zerotier/Api/SettingsController.php

@@ -48,6 +48,9 @@ class SettingsController extends ApiMutableModelControllerBase
         $result = array();
         if ($this->request->isGet()) {
             $mdlZerotier = $this->getModel();
+            if(empty($mdlZerotier->localconf->__toString())) {
+                $mdlZerotier->localconf = '{}';
+            }
             $result = array("zerotier" => $mdlZerotier->getNodes());
         }
         return $result;

net/zerotier/src/opnsense/service/templates/OPNsense/zerotier/local.conf

@@ -1,3 +1,5 @@
 {% if helpers.exists('OPNsense.zerotier.localconf') and OPNsense.zerotier.localconf|default("") != "" %}
 {{ OPNsense.zerotier.localconf }}
+{% else %}
+{}
 {% endif %}