ErrorException: Deprecated: unserialize(): Passing null to parameter #1 ($data) of type string is deprecated

[sentry-io]

Sentry Issue: BADGE-POSER-8J

ErrorException: Deprecated: unserialize(): Passing null to parameter #1 ($data) of type string is deprecated
  File "/src/Contributors/Service/Repository.php", line 87, in App\Contributors\Service\Repository::getContributorsByGithub
    $repoApi,
  File "/src/Contributors/Service/Repository.php", line 64, in App\Contributors\Service\Repository::getContributors
    $results = $this->getContributorsByGithub('PUGX', 'badge-poser');
  File "/src/Contributors/Service/Repository.php", line 31, in App\Contributors\Service\Repository::all
    return $this->getContributors();
  File "/src/Controller/HomeController.php", line 27, in App\Controller\HomeController::index
    $contributors = $contributorsRepository->all();
  File "/public/index.php", line 5
    require_once \dirname(__DIR__).'/vendor/autoload_runtime.php';
...
(36 additional frame(s) were not displayed)

[garak]

It looks like the problem is in the php-cache/cache library, in the fetchObjectFromCache method.
Maybe it could be addressed by this pull request, which is unfortunately stale since five years 😕