I have developed a login and signup feature using mobile OTP in FlutterFlow and Firebase. While everything works smoothly on the FlutterFlow run page, the app crashes completely when downloaded and run on an iPhone via TestFlight. I suspect the issue might be due to incorrect or incomplete iOS-specific configurations in either Firebase or FlutterFlow. Your task will be to: 1. Diagnose the root cause of the crash. 2. Ensure that all necessary iOS permissions and configurations for Firebase and FlutterFlow are correctly set up. 3. Provide a tested and fully functional solution that resolves the crash issue across iPhone devices. The deliverable should be a stable, crash-free app running smoothly on TestFlight for iPhones. Please ensure everything is documented and compatible with my current FlutterFlow-based app setup. Let me know if any additional details are required!