Fix "Warning: A non-numeric value encountered"

fixes php-enqueue/enqueue-dev#629

Author: makasim

Persister/QueuePagerPersister.php

@@ -111,7 +111,7 @@ public function insert(PagerInterface $pager, array $options = array())
                 $data = JSON::decode($message->getBody());
 
                 $errorMessage = $message->getProperty('fos-populate-error', false);
-                $objectsCount = $message->getProperty('fos-populate-objects-count', false);
+                $objectsCount = (int) $message->getProperty('fos-populate-objects-count', false);
 
                 $pager->setCurrentPage($data['page']);