App is crashing on click of cancel options on Visa supported card

[SrivastavaShubham99]

return await GoSellSdkFlutter.startPaymentSDK;

isUserAllowedToSaveCard: true,
isRequires3DSecure: true,
receipt: Receipt(true, true),
supportedPaymentMethods: ["visa", "APPLE_PAY"],

After this card appears with cancel options but when I click on it I am getting the following error and inside the SDK internal file :
goSellSDK/Process.DataManager.swift:408: Fatal error: Should be implemented in subclass.

Any suggestion would be appreciated