[Bug]: Facing AppId is null or format is invalid in Flutter iOS Only. Working in Android. AppID is not Null in Init Code.

What happened?

When I install my Flutter app on an iOS device, I always enconuter Error with message AppId is null or format is invalid. Although the AppID is not null/empty/of wrong format in the flutter init code. Works fine on Android.

Before you ask, I have:

Followed the Flutter SDK guide in the OneSignal documentation.
Paid Apple Developer Account.
Added the .p12 certificate to my OneSignal Account.
I am using a real iOS device with iOS 16.4.
Error Screenshot

Steps to reproduce?

1. Follow the FLutter SDK guide on OneSignal's Docs.
2. Run the app on iOS Device.

What did you expect to happen?

I expected the app to not crash.

OneSignal Flutter SDK version

onesignal_flutter: ^5.0.2

Which platform(s) are affected?

[X] iOS
[ ] Android

Relevant log output

(lldb) 2023-11-01 03:01:30.132503+0500 Runner[805:59021] [SceneConfiguration] Info.plist contained no UIScene configuration dictionary (looking for configuration named "(no name)")
[VERBOSE-2:FlutterDarwinContextMetalImpeller.mm(37)] Using the Impeller rendering backend.
Warning: Unable to create restoration in progress marker file
database path: /var/containers/Bundle/Application/E0930B29-65A5-4F98-8058-4ED3BF68EBD6/Runner.app/Frameworks/flutter_downloader.framework/FlutterDownloaderDatabase.bundle/download_tasks.sql
AllFilesDownloadedMessage: All files have been downloaded
FATAL: OneSignal AppId: (null) - AppId is null or format is invalid, stopping initialization.
Example usage: 'b2f7f966-d8cc-11e4-bed1-df8f05be55ba'
fopen failed for data file: errno = 2 (No such file or directory)
Errors found! Invalidating cache...
Connecting to VM Service at ws://127.0.0.1:61746/KNPSXVjZXvc=/ws
startBackgroundIsolate
[VERBOSE-2:FlutterDarwinContextMetalImpeller.mm(37)] Using the Impeller rendering backend.
*** Assertion failure in -[FlutterDownloaderPlugin startBackgroundIsolate:], FlutterDownloaderPlugin.m:152
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'failed to set registerPlugins'
*** First throw call stack:
(0x191041e48 0x18a3178d8 0x18b90694c 0x102616c5c 0x10261ca8c 0x10261fe44 0x105af3f0c 0x105558e1c 0x1986534b4 0x198654fdc 0x1986637f4 0x198663444 0x1910d26d8 0x1910b403c 0x1910b8ec0 0x1cb10f368 0x1935ae86c 0x1935ae4d0 0x1020f86b8 0x1af8da960)
libc++abi: terminating with uncaught exception of type NSException
* thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
    frame #0: 0x00000001ce9b3160 libsystem_kernel.dylib`__pthread_kill + 8
libsystem_kernel.dylib`:
->  0x1ce9b3160 <+8>:  b.lo   0x1ce9b3180               ; <+40>
    0x1ce9b3164 <+12>: pacibsp
    0x1ce9b3168 <+16>: stp    x29, x30, [sp, #-0x10]!
    0x1ce9b316c <+20>: mov    x29, sp
Target 0: (Runner) stopped.
Lost connection to device.

Code of Conduct

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OneSignal / OneSignal-Flutter-SDK

[Bug]: Facing AppId is null or format is invalid in Flutter iOS Only. Working in Android. AppID is not Null in Init Code. #781