Social landing page gives: Warning: array_flip(): Can only flip STRING and INTEGER values

Problem/Motivation

ge Warning: array_flip(): Can only flip STRING and INTEGER values! in Drupal\Core\Entity\EntityStorageBase->loadMultiple() (line 264 of /data/disk/o1/static/OS-5.5/html/core/lib/Drupal/Core/Entity/EntityStorageBase.php) #0 /data/disk/o1/static/OS-5.5/html/core/includes/bootstrap.inc(587): _drupal_error_handler_real(2, 'array_flip(): C...', '/data/disk/o1/s...', 264, Array) #1 [internal function]: _drupal_error_handler(2, 'array_flip(): C...', '/data/disk/o1/s...', 264, Array) #2 /data/disk/o1/static/OS-5.5/html/core/lib/Drupal/Core/Entity/EntityStorageBase.php(264): array_flip(Array) #3 /data/disk/o1/static/OS-5.5/html/core/lib/Drupal/Core/Entity/EntityStorageBase.php(249): Drupal\Core\Entity\EntityStorageBase->loadMultiple(Array) #4 /data/disk/o1/static/OS-5.5/html/core/lib/Drupal/Core/Entity/EntityBase.php(531): Drupal\Core\Entity\EntityStorageBase->load(NULL) #5 /data/disk/o1/static/OS-5.5/html/profiles/contrib/social/modules/social_features/social_landing_page/social_landing_page.module(285): Drupal\Core\Entity\EntityBase::load(NULL) #6 /data/disk/o1/static/OS-5.5/html/profiles/contrib/social/themes/socialbase/src/Plugin/Preprocess/Node.php(230): _social_landing_page_get_hero_image(Object(Drupal\node\Entity\Node)) #7 /data/disk/o1/static/OS-5.5/html/themes/contrib/bootstrap/src/Plugin/Preprocess/PreprocessBase.php(51): Drupal\socialbase\Plugin\Preprocess\Node->preprocessElement(Object(Drupal\bootstrap\Utility\Element), Object(Drupal\bootstrap\Utility\Variables)) #8 /data/disk/o1/static/OS-5.5/html/themes/contrib/bootstrap/src/Bootstrap.php(1405): Drupal\bootstrap\Plugin\Preprocess\PreprocessBase->preprocess(Array, 'node', Array) #9 /data/disk/o1/static/OS-5.5/html/themes/contrib/bootstrap/bootstrap.theme(118):

Steps to reproduce

Create Landing page with empty section.

Proposed resolution

Add check for empty section in _social_landing_page_get_hero_image()