type 'Null' is not a subtype of type 'Map<String, dynamic>' in type cast

[KenilDiyora]

Describe the bug

Calling Stripe.instance.collectBankAccount() successfully opens and completes the Stripe bank account collection UI, but after the flow finishes the Flutter app throws a runtime exception:

type 'Null' is not a subtype of type 'Map<String, dynamic>' in type cast

The exception appears to originate from ResultParser.parseError inside the stripe_platform_interface.

This occurs even though the bank account linking flow completes successfully.

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To Reproduce

Steps to reproduce the behavior:

1. Call Stripe.instance.collectBankAccount() with a valid clientSecret from the backend.
2. Complete the Stripe bank account collection UI.
3. After completion, the following exception is thrown.

Example code

    final result = await Stripe.instance.collectBankAccount(
      clientSecret: model.clientSecret ?? '',
      isPaymentIntent: false,
      params: CollectBankAccountParams(
        paymentMethodType: PaymentMethodType.USBankAccount,
        paymentMethodData: CollectBankAccountPaymentMethodData(
          billingDetails: BillingDetails(
            name: user?.getName(),
            email: user?.email,
          ),
        ),
      ),
    );

Exception

flutter: type 'Null' is not a subtype of type 'Map<String, dynamic>' in type cast

#0      _$StripeExceptionFromJson (package:stripe_platform_interface/src/models/errors.g.dart:26:23)
#1      new StripeException.fromJson (package:stripe_platform_interface/src/models/errors.dart:44:7)
#2      ResultParser.parseError (package:stripe_platform_interface/src/result_parser.dart:21:28)
#3      ResultParser.parse (package:stripe_platform_interface/src/result_parser.dart:16:13)
#4      MethodChannelStripe.collectBankAccount (package:stripe_platform_interface/src/method_channel_stripe.dart:590:7)
<asynchronous suspension>
#5      Stripe.collectBankAccount (package:flutter_stripe/src/stripe.dart:641:12)
<asynchronous suspension>

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Expected behavior

collectBankAccount() should complete without throwing an exception when the bank account collection flow finishes successfully.

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Smartphone / tablet

• Device: iOS Simulator and real iOS device (likely reproducible on Android as well)
• OS: iOS (tested on simulator and real device)
• Package version: flutter_stripe: ^12.3.0
• Flutter version: 3.35.3

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Additional context

• The bank account collection UI works correctly.
• The exception occurs after the UI flow completes.
• This seems related to ResultParser.parseError attempting to parse a null error object into Map<String, dynamic>.

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✅ This issue might be caused by null error handling in the platform interface when no error object is returned from native code.