Problem with Cache component and igbinary

[absumo]

Bug Report

Q	A
Critical Bug	no
Version	6.x.x

Problem description

The NavigationBuilder cache serializer fails when the php igbinary extension is installed.

Error:
Typed property Proxies\__CG__\ForkCMS\Modules\Extensions\Domain\ThemeTemplate\ThemeTemplate::$ must not be accessed before initialization (in __sleep)

  at vendor/symfony/cache/Marshaller/DefaultMarshaller.php:44
  at igbinary_serialize(array('main' => array(array(object(Page))), 'footer' => array(array(object(Page), object(Page))), 'root' => array(array(object(Page)))))
     (vendor/symfony/cache/Marshaller/DefaultMarshaller.php:44)
  at Symfony\Component\Cache\Marshaller\DefaultMarshaller->marshall(array('pages_grouped_en' => array('main' => array(array(object(Page))), 'footer' => array(array(object(Page), object(Page))), 'root' => array(array(object(Page))))), array())
     (vendor/symfony/cache/Traits/FilesystemTrait.php:86)
  at Symfony\Component\Cache\Adapter\FilesystemAdapter->doSave(array('pages_grouped_en' => array('main' => array(array(object(Page))), 'footer' => array(array(object(Page), object(Page))), 'root' => array(array(object(Page))))), 0)
     (vendor/symfony/cache/Adapter/AbstractAdapter.php:148)
  at Symfony\Component\Cache\Adapter\AbstractAdapter->commit()
     (vendor/symfony/cache/Traits/AbstractAdapterTrait.php:239)
  at Symfony\Component\Cache\Adapter\AbstractAdapter->save(object(CacheItem))
     (vendor/symfony/cache/Adapter/TraceableAdapter.php:108)
  at Symfony\Component\Cache\Adapter\TraceableAdapter->save(object(CacheItem))
     (src/Modules/Pages/Domain/Page/NavigationBuilder.php:173)
  at ForkCMS\Modules\Pages\Domain\Page\NavigationBuilder->getGroupedPages(object(Locale))
     (src/Modules/Pages/Domain/Page/NavigationBuilder.php:49)
  at ForkCMS\Modules\Pages\Domain\Page\NavigationBuilder->getTree(object(Locale))
     (src/Modules/Pages/Backend/Actions/PageIndex.php:25)
  at ForkCMS\Modules\Pages\Backend\Actions\PageIndex->execute(object(Request))
     (src/Modules/Backend/Domain/Action/AbstractActionController.php:69)
  at ForkCMS\Modules\Backend\Domain\Action\AbstractActionController->__invoke(object(Request))
     (src/Modules/Backend/Controller/BackendController.php:54)
  at ForkCMS\Modules\Backend\Controller\BackendController->__invoke(object(Request), object(ActionSlug))
     (vendor/symfony/http-kernel/HttpKernel.php:166)
  at Symfony\Component\HttpKernel\HttpKernel->handleRaw(object(Request), 1)
     (vendor/symfony/http-kernel/HttpKernel.php:74)
  at Symfony\Component\HttpKernel\HttpKernel->handle(object(Request), 1, true)
     (vendor/symfony/http-kernel/Kernel.php:197)
  at Symfony\Component\HttpKernel\Kernel->handle(object(Request))
     (public/index.php:20)                

Steps to reproduce

Install the igbinary extension, run php bin/console c:p:c --all, open /private/en/pages/page-index.

Expected behavior / Proposed solution

Probably introduced somewhere after c2a65e6d5