Check if any gateways exist before iterating

[jiuka]

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Describe the bug

On a fresh OPNsense configuration the key /opnsense/gateways does not exist in the config.xml. If a Gateway is created and then deleted an error is raise.

foreach() argument must be of type array|object, null given

To delete the gateway a gateway group needs to be createt (and can be deleted again). This leafs the following in the config.xml.

  <gateways>
    <gateway_group/>
  </gateways>

To Reproduce

Steps to reproduce the behavior:

1. Delete the gateways node from config.xml
2. Create a Gateway
3. Delete the Gateway
4. See error

Expected behavior

The gateway should be deleted.

Describe alternatives you considered

Screenshots

Relevant log files

[10-Oct-2024 15:04:52 Etc/UTC] ErrorException: foreach() argument must be of type array|object, null given in /usr/local/opnsense/mvc/app/controllers/OPNsense/Routing/Api/SettingsController.php:208
Stack trace:
#0 /usr/local/opnsense/mvc/app/controllers/OPNsense/Routing/Api/SettingsController.php(208): {closure}(2, 'foreach() argum...', '/usr/local/opns...', 208)
#1 /usr/local/opnsense/mvc/app/library/OPNsense/Mvc/Dispatcher.php(165): OPNsense\Routing\Api\SettingsController->delGatewayAction('bcad02aa-a52d-4...')
#2 /usr/local/opnsense/mvc/app/library/OPNsense/Mvc/Router.php(156): OPNsense\Mvc\Dispatcher->dispatch(Object(OPNsense\Mvc\Request), Object(OPNsense\Mvc\Response), Object(OPNsense\Mvc\Session))
#3 /usr/local/opnsense/mvc/app/library/OPNsense/Mvc/Router.php(139): OPNsense\Mvc\Router->performRequest(Object(OPNsense\Mvc\Dispatcher))
#4 /usr/local/opnsense/www/api.php(36): OPNsense\Mvc\Router->routeRequest('/api/routing/se...', Array)
#5 {main}

Additional context

Environment

Software version used and hardware type if relevant, e.g.:

OPNsense 24.7.6-amd64