Fix: foreach() argument must be of type array|object

[Rom1-B]

Checklist before requesting a review

Please delete options that are not relevant.

• I have performed a self-review of my code.
• I have added tests (when available) that prove my fix is effective or that my feature works.
• I have updated the CHANGELOG with a short functional description of the fix or new feature.
• This change requires a documentation update.

Description

• It fixes !38732

Avoid this error in the logs:

glpi.WARNING:   *** Warning: foreach() argument must be of type array|object, null given at container.class.php line 244
  Backtrace :
  ./marketplace/fields/inc/container.class.php:244   
  ./marketplace/fields/hook.php:87                   PluginFieldsContainer::installUserData()
  ./src/Plugin.php:1160                              plugin_fields_install()
  :                                                  Plugin->install()
  ./src/Glpi/Marketplace/Controller.php:655          call_user_func()
  ./src/Glpi/Marketplace/Controller.php:545          Glpi\Marketplace\Controller->setPluginState()
  ./ajax/marketplace.php:63                          Glpi\Marketplace\Controller->installPlugin()
  ...Glpi/Controller/LegacyFileLoadController.php:64 require()
  ./vendor/symfony/http-kernel/HttpKernel.php:181    Glpi\Controller\LegacyFileLoadController->__invoke()
  ./vendor/symfony/http-kernel/HttpKernel.php:76     Symfony\Component\HttpKernel\HttpKernel->handleRaw()
  ./vendor/symfony/http-kernel/Kernel.php:197        Symfony\Component\HttpKernel\HttpKernel->handle()
  ./public/index.php:70                              Symfony\Component\HttpKernel\Kernel->handle()

Screenshots (if appropriate):