Stripe VC Crash.swift

//class that generates the ephermal key
class StripeCustomerSessionManager: NSObject, STPEphemeralKeyProvider {

    func createCustomerKey(withAPIVersion apiVersion: String, completion: @escaping STPJSONResponseCompletionBlock) {
        
        let parameters = [
            "api_version": apiVersion
        ]
        
      //this runs async, could this be causing an issue? i think the app crashes before it runs though
      //i commented out the next part and the app still crashed
        Alamofire.request(Constants.apiBaseUrl() + "user/stripe/key", method: .post, parameters: parameters, encoding: URLEncoding.default, headers: APIManager.generateHeaders())
            .validate(statusCode: 200..<300)
            .responseJSON { responseJSON in
                print(responseJSON.response)
                print(responseJSON.result)
                switch responseJSON.result {
                case .success(let json):
                    completion(json as? [String: AnyObject], nil)
                case .failure(let error):
                    completion(nil, error)
                }
        }
    }
}

//issuing stripe key on the backend - python
def issue_stripe_key(request):
    # api_version = request.POST['api_version']
    customerId = request.user.stripe_customer_id
    key = stripe.EphemeralKey.create(customer=customerId, api_version="2018-11-08")
    return JsonResponse(data=key)

//stack trace on Firebase Crashlytics - lines 2 and 29 are highlighted
Fatal Exception: NSInvalidArgumentException
0  CoreFoundation                 0x1969e3ea0 __exceptionPreprocess
1  libobjc.A.dylib                0x195bb5a40 objc_exception_throw
2  CoreFoundation                 0x1968fcd04 -[NSOrderedSet initWithSet:copyItems:]
3  UIKitCore                      0x1c3bdeb38 -[UIResponder doesNotRecognizeSelector:]
4  Stripe                         0x106ae1904 (Missing)
5  CoreFoundation                 0x1969e94b4 ___forwarding___
6  CoreFoundation                 0x1969eb45c _CF_forwarding_prep_0
7  UIKitCore                      0x1c35ef9cc -[UIViewController _setViewAppearState:isAnimating:]
8  UIKitCore                      0x1c354cf14 -[UINavigationController viewDidAppear:]
9  UIKitCore                      0x1c35ef9cc -[UIViewController _setViewAppearState:isAnimating:]
10 UIKitCore                      0x1c35f034c -[UIViewController _endAppearanceTransition:]
11 UIKitCore                      0x1c3511f60 -[UIPresentationController transitionDidFinish:]
12 UIKitCore                      0x1c351b220 -[_UICurrentContextPresentationController transitionDidFinish:]
13 UIKitCore                      0x1c3516154 __56-[UIPresentationController runTransitionForCurrentState]_block_invoke.440
14 UIKitCore                      0x1c3614090 -[_UIViewControllerTransitionContext completeTransition:]
15 UIKitCore                      0x1c4015f4c -[UITransitionView notifyDidCompleteTransition:]
16 UIKitCore                      0x1c4015be4 -[UITransitionView _didCompleteTransition:]
17 UIKitCore                      0x1c4017cf4 -[UITransitionView _transitionDidStop:finished:]
18 UIKitCore                      0x1c4020154 -[UIViewAnimationState sendDelegateAnimationDidStop:finished:]
19 UIKitCore                      0x1c4020740 -[UIViewAnimationState animationDidStop:finished:]
20 UIKitCore                      0x1c40207e0 -[UIViewAnimationState animationDidStop:finished:]
21 QuartzCore                     0x19afe85d0 CA::Layer::run_animation_callbacks(void*)
22 libdispatch.dylib              0x19641e484 _dispatch_client_callout
23 libdispatch.dylib              0x1963ca9b4 _dispatch_main_queue_callback_4CF$VARIANT$mp
24 CoreFoundation                 0x196973dd0 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__
25 CoreFoundation                 0x19696ec98 __CFRunLoopRun
26 CoreFoundation                 0x19696e1cc CFRunLoopRunSpecific
27 GraphicsServices               0x198be5584 GSEventRunModal
28 UIKitCore                      0x1c3bb1054 UIApplicationMain
29 Visavis                        0x104b09bd8 main (AppDelegate.swift:25)
30 libdyld.dylib                  0x19642ebb4 start