Steps to reproduce:
1. Make sure the iOS player is installed to avoid console errors
2. Open the “user’s attached project”
3. Go to File/Build Profiles through the Main Menu
4. Switch the Build Profile to WebGL
5. Select any of the following Code Optimization options: Runtime Speed, Runtime Speed with LTO, Disk Size, Disk Size with LTO
5. Build and Run
6. Observe the error after the build has finished

Reproducible with versions: 6000.0.55f1, 6000.1.16f1, 6000.2.0f1, 6000.3.0a4
Couldn’t test with versions: 2021.3.54f1, 2022.3.65f1, 2023.2.20f1 (due to compiler and package errors)

Reproducible on: macOS 15.5 (M1 Max), Windows 11 (user)
Not reproducible on: no other environment tested

Note: not reproducible when running a Development Build

Workarounds:
- Disabling string compression when saving prefs in WebGL
- Disabling the "Compress Responses" option in Playfab settings