message: add random failure into payment refund
diff: @@ -4,6 +4,10 @@ export {};
  exports.handler = async function(event:any) {
  console.log("request:", JSON.stringify(event, undefined, 2));
  + if (Math.random() < 0.4) {
  + throw new Error("Internal Server Error");
  + }
  +
  let paymentID = '';
  if (typeof event.TakePaymentResult !== 'undefined') {
  paymentID = event.TakePaymentResult.payment_id;
  