500 Error on Error: Call to a member function getSiteResolver() on null in Drupal\next\Controller\SitePreviewController->nodePreview() (line 71

Steps -

Setup ACMS headless mode site
Visit the site home page
Click on "Preview" tab
Error is triggering because of SitePreviewController::nodePreview() line - $sites = $next_entity_type_config->getSiteResolver()->getSitesForEntity($revision);

As there is no nextjs site is configured (and also as per definition of getSiteResolver()), getSiteResolver() return NULL and thus the error.