pp_express.php payment_status notice on line 1646

Who can tell me what is wrong?
This has not happened before

My oc version is 2.3.0.2

oc admin panel error log：
xxxxxx - PHP Notice: Undefined index: payment_status in /web/catalog/controller/extension/payment/pp_express.php on line 1646
xxxxxx - PHP Notice: Undefined index: payment_status in /web/catalog/controller/extension/payment/pp_express.php on line 1647

web log：
173.0.81.1 - - [xxxxx] "POST /index.php?route=extension/payment/pp_express/ipn HTTP/1.1" 200 5 "-" "PayPal IPN ( https://www.paypal.com/ipn )"

Are there any other problems with the site? Are payment statuses being set correctly from PayPal? If all else seems to be ok then this might not be a problem because these are only "notices".