payment-api.js:101 Uncaught DOMException: Failed to construct 'PaymentRequest': Must be in a secure context
If you see above error, you must doing Android Pay on web.
Above link explained the expection. it is a "secure context" error.
What is "secure context" error?
localhost is secure context. https is secure context.
which means you can only test your Android Pay web app with localhost, or on a https domain.