Deprecated function: explode() after updating PHP to version 8.1

[jolimas]

After updating PHP from v7.4 to v8.1 I get this warning:

"Deprecated function: explode(): Passing null to parameter #2 ($string) of type string is deprecated at Drupal\gigya_raas\GigyaController->getGigyaLoginToken() (line 570 de /app/docroot/modules/contrib/gigya-drupal/gigya_raas/src/GigyaController.php)"