Refund credit card payment paypall

I am trying to refund a payment made by card using Paypal but I have an error 500 on refund

{ name: 'INTERNAL_SERVICE_ERROR',
  message: 'An internal service error occurred.',
  information_link: 'https://developer.paypal.com/webapps/developer/docs/api/#INTERNAL_SERVICE_ERROR',
  debug_id: '4791f4fde5314',
  httpStatusCode: 500 
},

My code is

const paypal = require('paypal-rest-sdk');
const creditCardType = require('credit-card-type');
const util = require('util')

const card = creditCardType('4111111111111111');

paypal.configure({
  'mode': 'sandbox', //sandbox or live
  'client_id': 'id',
  'client_secret': 'secret'
});

const paymentObj = {
    intent: 'sale',
    payer: {
        payment_method: 'credit_card',
        funding_instruments: [{
            'credit_card': {
                number: '4111111111111111',
                type: card[0].type,
                'expire_month': 11,
                'expire_year': 2019,
                cvv2: 123,
                'first_name': 'Jon Doe'
            }
        }]
    },
    transactions: [{
        amount: {
            total: '12.12',
            currency: 'EUR'
        }
    }]
};
console.log(util.inspect(paymentObj, false, null));

paypal.payment.create(paymentObj, (error, payment) => {
    if(error) console.log(util.inspect(error, false, null));
    console.log(util.inspect(payment, false, null));
    paypal.sale.refund(payment.id, {
        amount: {
            total: '1.99',
            currency: 'EUR'
        }
    }, (error, response) => {
        if(error) console.log(util.inspect(error, false, null));
        console.log(util.inspect(response, false, null));
    })
})

I don't understand, I am not sure I have to capture the payment if this is a card payment, following the doc I shouldn't I tried paypal.sale.refund, I don't know fi there is an other way.

via ant