Apply fix to query idInsideBundle for documentCategory creation

src/Bundle/ChillDocStoreBundle/Controller/DocumentCategoryController.php

@@ -92,13 +92,14 @@ class DocumentCategoryController extends AbstractController
 
         $nextId = $em
             ->createQuery(
-                'SELECT MAX(c.idInsideBundle) + 1 FROM ChillDocStoreBundle:DocumentCategory c'
+                'SELECT (CASE WHEN MAX(c.idInsideBundle) IS NULL THEN 1 ELSE MAX(c.idInsideBundle) + 1 END)
+         FROM ChillDocStoreBundle:DocumentCategory c'
             )
-            ->getSingleResult();
+            ->getSingleScalarResult();
 
         $documentCategory = new DocumentCategory(
             ChillDocStoreBundle::class,
-            reset($nextId)
+            $nextId
         );
 
         $documentCategory