Error: Must provide exactly one of these parameters: [:customer, :issuing_card] - ios

Question

I am trying to integrate the Stripe API inside of my application using firebase cloud functions as my backend. I get the error listed above when I make a call to create an ephemeral key.
This is what my client side set up look like :
func createCustomerKey(withAPIVersion apiVersion: String, completion: #escaping STPJSONResponseCompletionBlock) {
let url = self.baseURL.appendingPathComponent("/ephemeral_keys")
Alamofire.request(url, method: .post, parameters: [
"api_version": apiVersion,"customer": "cus_somethingsomething"
])
.validate(statusCode: 200..<400)
.responseJSON { responseJSON in
switch responseJSON.result {
case .success(let json):
completion(json as? [String: AnyObject], nil)
case .failure(let error):
completion(nil, error)
}
}
}
and here is my server side index.js file look like:
exports.StripeEphemeralKeys = functions.https.onRequest((req, res) => {
const stripe_version = req.body.api_version;
const customer = req.body.customer_id;
stripe.ephemeralKeys.create(
{customer: customer},
{apiVersion: stripe_version}
).then((key) => {
res.status(200).send(key)
return admin.database().ref(`/strcustomers/tempkey`).set(key);
}).catch((err) => {
console.log('Inside error, fetching key failed', err)
});
});
I am providing a customer parameter already so I don't understand why I'm getting this error. There may be something I'm missing and could definitely use some help had anybody ran into similar issue before.
Here is the link of the tutorial I followed : https://www.iosapptemplates.com/blog/ios-development/stripe-firebase-swift