Issue in displaying card in stripe payment intigration

I want to intigrate stripe payment but i got this error Instance of 'StripeConfigException Also my when i click on pay button it is not showing any type of card. I want to print jsonresponse["emphermalKey"] and jsonresponse["customer"] but these show null value.I also put api key correctly . Please solve my issue i am stuck in stripe payment for couple of days Here is my stripe log which shoes null value.

{
 "customer": null,
  "description": null,
  "invoice": null,
  "last_payment_error": null,
  "latest_charge": null,
"next_action": null,
  "on_behalf_of": null,
  "payment_method": null,
"payment_method_options": {
    "card": {
      "installments": null,
      "mandate_options": null,
      "network": null,
      "request_three_d_secure": "automatic"
    }
"processing": null,
  "review": null,
  "setup_future_usage": null,
  "shipping": null,
  "source": null,
  "statement_descriptor": null,
  "statement_descriptor_suffix": null,
  "status": "requires_payment_method",
  "transfer_data": null,
  "transfer_group": null
}

my code

Center(
        child: ElevatedButton(
          onPressed: () {
            intpayment(email: "email,amount: 50.0);
            },
          child: Text("Pay20\$"),
        ),
      ),

Function

Future<void> intpayment(
      {required String email, required double amount})async{
    try{
      final response= await http.post(Uri.parse("https://api.stripe.com/v1/payment_intents")
          ,body:{
            "receipt_email": email,
            "amount": amount.toInt().toString(),
            "currency": "usd"
          },
          headers: {
            'Authorization': 'Bearer ' + 'key',
            'Content-Type': 'application/x-www-form-urlencoded'
          }
      );
      final jsonresponse=jsonDecode(response.body);      Stripe.instance.initPaymentSheet(paymentSheetParameters: SetupPaymentSheetParameters(
        paymentIntentClientSecret: jsonresponse['paymentIntent'],
        merchantDisplayName: 'Zohaib',
        customerId: jsonresponse['customer'],
        customerEphemeralKeySecret: jsonresponse['ephemeralKey'],
      ));
      await Stripe.instance.presentPaymentSheet();
      Fluttertoast.showToast(
          msg: "payment successfully",
      );
    }
    catch(e){
      if (e is StripeException) {
        Fluttertoast.showToast(
            msg: "Stripe error $e",
        );
      }
      Fluttertoast.showToast(
          msg: "$e",
          toastLength: Toast.LENGTH_SHORT, );
    }
  }

I think issue in this line when I comment out this the error remove but card is not displying

  await Stripe.instance.presentPaymentSheet();