Se cambia nombre de la variable.

Controller/RESTController.php

@@ -68,8 +68,8 @@ class RESTController extends VoryxController
                     $criteria->orderBy($orderBy);
                 }
 
-                $clients = $em->getRepository($this->repository);
-                $entities = $clients->matching($criteria)->toArray();
+                $repo = $em->getRepository($this->repository);
+                $entities = $repo->matching($criteria)->toArray();
 
                 if ($entities) {
                     return $entities;