Merge pull request #525 from EmanueleMinotto/unused-code

remove unused `$previousException`

Author: gfosco

src/Facebook/Exceptions/FacebookResponseException.php

@@ -77,8 +77,6 @@ public static function create(FacebookResponse $response)
         $code = isset($data['error']['code']) ? $data['error']['code'] : null;
         $message = isset($data['error']['message']) ? $data['error']['message'] : 'Unknown error from Graph.';
 
-        $previousException = null;
-
         if (isset($data['error']['error_subcode'])) {
             switch ($data['error']['error_subcode']) {
                 // Other authentication issues