Issue-3473888: Fixed configuration page issue.

Closes #3473888

src/Entity/MarkItViewsData.php

@@ -48,9 +48,12 @@ class MarkItViewsData extends EntityViewsData {
     $configuration = $this->configFactory->get('markit.settings');
     $target_entity_bundles = $configuration->get('target_entities');
     $target_entity_types = [];
-    foreach ($target_entity_bundles as $target_entity_bundle) {
-      list($entity_type,) = explode(':', $target_entity_bundle);
-      $target_entity_types[$entity_type] = $entity_type;
+    $is_arr_or_obj = is_array($target_entity_bundles) || is_object($target_entity_bundles);
+    if ($is_arr_or_obj) {
+      foreach ($target_entity_bundles as $target_entity_bundle) {
+        list($entity_type,) = explode(':', $target_entity_bundle);
+        $target_entity_types[$entity_type] = $entity_type;
+      }
     }
 
     // Loop over the entity_types and build proper relationships.

[Panagiotis Moutsopoulos]

Changing L49 to $target_entity_bundles = $configuration->get('target_entities') ?? []; wouldn't solve the issue here?