To reproduce:
1. Open attached project
2. Open "game" scene
3. Open Animation window
4. Build for iOS
5. Select "_GameController" game object in the Hierarchy
6. Change Coin Value, Sack Value, Vault Value to any values in the Game Balance component
7. Build for iOS

Actual behavior: second build fails with errors: "EnsureRunningOnMainThread is not allowed to be called during serialization, call it from Awake or Start instead. Called from MonoBehaviour 'CollectionScreen' on game object '6 Collection'.
See "Script Serialization" page in the Unity Manual for further details."

Workaround: close Animation window before building

Regression from 5.3 to 5.4