How to reproduce:

1. Open the attached "IN-138759" project
2. Ensure that 'Strip Engine Code' is enabled in the Player Settings
3. Go to Window > Package management > Package Manager > Built-in and ensure that the Tilemap package module is disabled
4. Build and Run the Player
5. Once the build is launched, press F12 to open the browser console
6. Observe the error: "Could not produce class with ID 331"

Actual result: "Could not produce class with ID 331" error occurs, and the SpriteMask doesn't draw
Expected result: The SpriteMask is included in the project and no errors are shown

Reproducible with: 6000.0.72f1, 6000.3.12f1, 6000.4.1f1, 6000.5.0b1, 6000.6.0a2

Reproducible environment: Android, iOS (by reporter), Web
Not reproducible environment: Windows (Doesn’t have “Strip Engine Code”)

Workaround: Enable the Tilemap package module in the Package Manager (Built-in window)