优化订单状态逻辑

public/order.php

@@ -1,4 +1,9 @@
 <?php
+
 header('content-type: application/json; charset=utf-8');
-$order = file_get_contents('../runtime/order.json');
-echo $order;
+$path = '../runtime/order.json';
+if (!file_exists($path)) {
+    exit('{"code":3,"msg":"文件不存在"}');
+} else {
+    exit(file_get_contents($path));
+}