How to reproduce:

1. Open attached project
2. Build to iOS and run
- Note the error in the Xcode log:
- NullReferenceException: UnityWebRequest has already been destroyed
at UnityEngine.Networking.UnityWebRequest.set_url (System.String value) [0x00000] in <filename unknown>:0
at SimpleTest+<GetText>c__Iterator0.MoveNext () [0x00000] in <filename unknown>:0
- Reproduced in Version 5.4.0b1 (3137382c8e08), Version 5.3.1f1 (3b3e8231502f)
- Blocked from testing older versions due to errors
- The error is not reproducible when Strip Engine Code option is enabled and when building using Mono2x