How to reproduce:
1. Open the “iOSCrashTest.zip“ project
2. Open the “SampleScene“
3. Choose the iOS build module
4. Navigate to the “File > Build Settings“
5. Set “Run in Xcode as“ to Debug
6. Enable Development Build
7. Build for iOS
8. Open the “Unity-iPhone.xcodeproj“ in Xcode
9. Build to a device

Expected result: No crash
Actual result: Crash on startup

Reproducible with: 2023.1.15f1, 2023.2.5f1, 2023.3.0b2 , 6000.0.57f1, 6000.2.3f1, 6000.3.0b1
Not reproducible with: 2022.3.66f1
Could not test with: 2023.1 (steam from 2023.1.0a1 to 2023.1.14f1 has a bug that prevents testing, more in the comment)

Reproducible environment: macOS 15.6.1 (M4 Max)
Not reproducible environment: No other environment tested

Reproducible with these devices:
macOS 15.6.1 Standalone with the Xcode created project
VLNQA00416, iPhone 13 Pro (MLVA3ET/A), CPU: Apple A15 Bionic, OS: 16.1.1
VLNQA00535, iPhone XS (MT9F2ET/A), CPU: Apple A12 Bionic, OS: 17.6.1
VLNQA00232, iPhone 8 Plus (MQ8M2ET/A), CPU: Apple A11 Bionic, OS: 16.7.10
VLNQA00626, iPhone 16 (MYE73QN/A), CPU: Apple A18 Pro, OS: 18.5

Workaround: use ‘null' in the signature and move the logic for assigning a default value into the method body using the null-coalescing operator '??’