Payment Options View Controller (for Stripe) Not Showing Up - node.js

Question

I am fairly new to this. I have used cloud functions and firebase to integrate stripe into my iOS project. Here is my code for the payment options (in node.js).
exports.addPaymentMethodDetails = functions.firestore
.document('/stripe_customers/{userId}/payment_methods/{pushId}')
.onCreate(async (snap, context) => {
try {
const paymentMethodId = snap.data().id;
const paymentMethod = await stripe.paymentMethods.retrieve(
paymentMethodId
);
await snap.ref.set(paymentMethod);
// Create a new SetupIntent so the customer can add a new method next time.
const intent = await stripe.setupIntents.create({
customer: paymentMethod.customer,
});
await snap.ref.parent.parent.set(
{
setup_secret: intent.client_secret,
},
{ merge: true }
);
return;
} catch (error) {
await snap.ref.set({ error: userFacingMessage(error) }, { merge: true });
await reportError(error, { user: context.params.userId });
}
})
Here is my code in Xcode:
``let customerContext = STPCustomerContext(keyProvider: StripeApi)
var paymentContext: STPPaymentContext!
init() {
self.paymentContext = STPPaymentContext(customerContext: customerContext)
super.init(nibName: nil, bundle: nil)
self.paymentContext.delegate = self
self.paymentContext.hostViewController = self
self.paymentContext.paymentAmount = 5000 // This is in cents, i.e. $50 USD
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
#IBAction func paymentMethodClicked(_ sender: Any) {
paymentContext.pushPaymentOptionsViewController()
}
func setupStripeConfig() {
let config = STPPaymentConfiguration.shared()
config.additionalPaymentOptions = .default
config.requiredBillingAddressFields = .none
let customerContext = STPCustomerContext(keyProvider: StripeApi)
paymentContext = STPPaymentContext(customerContext: customerContext, configuration: config, theme: .default())
paymentContext.delegate = self
paymentContext.hostViewController = self
When I run the simulator of this and click the button to pull up payment options, nothing happens and my console (in Xcode) reads "INTERNAL". Can someone please show me how to bring up the Payment Options View Controller, or if there is something I need to or add/fix in order to do so? Also here is my node.js code for getting an ephemeral key:
exports.createEphemeralKey = functions.https.onCall(async (data, context) => {
const customerID = data.customer_id;
const stripeVersion = data.stripe_version;
const uid = context.auth.uid;
if (uid === null) {
console.log('Illegal access attempt due to unauthenticated user');
throw new functions.https.HtppsError('permission-denied', 'Illegal access attempt')
}
let key = await stripe.ephemeralKeys.create(
{customer: '{{CUSTOMER_ID}}'},
{stripe_version: '{{API_VERSION}}'}
);
return stripe.ephemeralKeys.create(
{customer: customerID},
{stripe_version: stripeVersion}).then((key) => {
return key
}).catch((err) => {
console.log(err)
throw new functions.https.HttpsError9('internal', 'Unable to create ephemeral key.')
});
});