fix: PayPal, 缺少custom id

webht/third_party/paypal/controllers/index.php

@@ -734,10 +734,10 @@ class Index extends CI_Controller {
                 break;
 
             case 'PAYMENT.CAPTURE.COMPLETED':
-            case 'PAYMENT.CAPTURE.DECLINED': // todo: CHECKOUT.PAYMENT-APPROVAL.REVERSED
+            case 'PAYMENT.CAPTURE.DECLINED': // todo: CHECKOUT.PAYMENT-APPROVAL.REVERSED  PAYMENT.CAPTURE.PENDING
                 $fund_type = 'pay';
                 $pn_invoice = $post_data->resource->invoice_id;
-                $pn_custom = $post_data->resource->custom_id;
+                $pn_custom = isset($post_data->resource->custom_id) ? $post_data->resource->custom_id : '';
                 $pn_mc_gross = $post_data->resource->amount->value;
                 $pn_mc_currency = $post_data->resource->amount->currency_code;
                 $pn_payment_status = $post_data->resource->status;