Reproduction steps:
1. Open project in "New Unity Project.zip"
2. Build for iOS and deploy the application using XCode
3. Press "Allow" when prompted to receive notifications
4. A notification will be scheduled with a null title ("Notifications.cs")

Expected result: either a notification with an empty title is shown (like on Android)
Actual result: application crashes on signal SIGABRT due to uncaught exception "NULL cString"

Reproducible with: Mobile Notifications 1.0.2 (2018.4.27f1), Mobile Notifications 1.3.0 (2018.4.27f1, 2019.4.10f1, 2020.1.5f1, 2020.2.0b2)

Not reproducible with Android: an empty notification appears if using a null title and/or body

Devices tested:
Reproducible with:
VLNQA00310 iPad Pro 12.9 1st gen (iOS 13.4.1)
VLNQA00204 iPhone 5C (iOS 10.3.3)
Not reproducible with:
OnePlus A5000, Android 10, Adreno 540, Snapdragon 835

Notes:
1. If you want to test on Android use "AndroidNotifications.cs" script
2. XCode console indicates an uncaught exception

Few lines from stack trace (full stack in edits, look for lldb):
thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
frame #0: 0x00000001b5604d88 libsystem_kernel.dylib`__pthread_kill + 8
...
* frame #13: 0x00000001027a7e1c Notifications`main(argc=<unavailable>, argv=<unavailable>) at main.mm:26:9 [opt]
frame #14: 0x00000001b560f800 libdyld.dylib`start + 4