another way to fix phonenumber and telephone in third party / OnTheFly

src/Bundle/ChillMainBundle/Serializer/Normalizer/PhonenumberNormalizer.php

@@ -40,6 +40,10 @@ class PhonenumberNormalizer implements NormalizerInterface, DenormalizerInterfac
      */
     public function denormalize($data, $type, $format = null, array $context = [])
     {
+        if ('' === trim($data)) {
+            return null;
+        }
+
         try {
             return $this->phoneNumberUtil->parse($data, $this->defaultCarrierCode);
         } catch (NumberParseException $e) {