fix: Undefined array key "entities_id"

Author: JeremieMercier

inc/container.class.php

@@ -1706,7 +1706,7 @@ public static function findContainers($itemtype, $type = 'tab', $subtype = '', $
             $obj = new $itemtype();
             if ($obj->getFromDB($itemId)) {
 
-                $entityId = $obj->fields['entities_id'];
+                $entityId = $obj->fields['entities_id'] ?? 0;
                 $entityIds = getAncestorsOf("glpi_entities", $entityId);
                 $entityIds[] = $entityId; // Add entity obj itself to the list
                 $glpiActiveEntities = $_SESSION['glpiactiveentities'] ?? 0;