Merge pull request #2 from mhh1422/master

Bug fix

Author: mhh1422

src/ElasticSessionStore.php

@@ -47,7 +47,6 @@ public static function putMapping() {
                 ]
             ]
         ];
-        dd(json_encode($mappingParams));
         $client->indices()->putMapping($mappingParams);
     }
 
@@ -65,6 +64,9 @@ public function gc($maxLifeTime) {
 
     public function read($sessionId) {
         $model = @$this->find($sessionId);
+        if (!$model) {
+            return null;
+        }
         $this->_cache[$sessionId] = $model;
         return $model->data;
     }