Fix bug when address info is empty

data/logic/buy.logic.php

@@ -181,7 +181,9 @@ class buyLogic {
         $result['freight_list'] = $this->buyEncrypt($freight_list, $member_id);
 
         //输出用户默认收货地址
-        $result['address_info'] = Model('address')->getDefaultAddressInfo(array('member_id'=>$member_id));
+        $address_info = Model('address')->getDefaultAddressInfo(array('member_id'=>$member_id));
+
+        $result['address_info'] = empty($address_info)? null : $address_info;
 
         //输出有货到付款时，在线支付和货到付款及每种支付下商品数量和详细列表
         $pay_goods_list = $this->_logic_buy_1->getOfflineGoodsPay($goods_list);