Fic IONIC 3 error -- IOS

I need someone about some bug fixing of an IOS app build in IONIC 3. The android version of the app is working perfectly , but I am facing problems with the IOS one. I have integrated the paypal payment gateway. Every time I am trying to enter the gateway, I am facing errors and app crashed. I am testing the app on simulator, as I don't have any IPHONE device. The fixing is very important for me, as I have already crossed the deadline. Need this error fixed ASAP. Including the screenshots.