修复在线客服获取不到数据时会报错的bug

Code Review By Rock Zhang

@@ -19,10 +19,10 @@ class OnlineModel
     {
         //调用接口获取数据
         $res = OnlineData::getOnlineServiceInfo($clientType);
-        $cateInfo = $res['data'];
         $question = array();
         $tab = array();
-        if ($cateInfo) {
+        if (isset($res['data'])) {
+            $cateInfo = $res['data'];
             foreach ($cateInfo as $key => $value) {
                 //强制截成3个tab
                 if ($key > 2) {