Freecharge 'Nothing to see here' error

I have been trying to use the Freecharge site to use up a coupon code.
The log-in is fine, the coupon gets applied too, but on clicking the ‘pay from wallet’ button as final step, its going to an error page “Nothing to see here”. There is a “Go back to Home” button below it.

A possible thing I could find is, that the page where the payment method is chosen + coupon is applied, has a ‘?undefined’ at the end of the URL string. Can that be related to this?
The URL string is “https://www.freecharge.in/mobile/payment/pay/**... string)*/?undefined”

Any one had same issue or knows what may be causing this?
Thanks in advance.