We are trying to add Apple Pay to our existing web site. I have the payment sheet popping up, and am seeing the call to onvalidatemerchant which in turn calls our server that returns what looks to be a valid Merchant Session object, but when I call completeMerchantValidation with the object I get a Type Error with no other information.
Has anyone come across this and found a way to resolve the error. I am testing on an iPad Mini with iOS 10.2.1.