Steps to reproduce:

1. Open the attached project
2. Open any scene
3. In the Hierarchy panel, create an empty GameObject
3. Make sure the Lighting Settings or Animation Parameter window is open
4. Enter Play Mode

Reproducible with: 2017.2.3p2, 2017.4.6f1, 2018.1.6f1, 2018.2.0b10, 2018.3.0a3
Not reproducible with: 2017.1.4p2f

Notes:

Reproducible with AssetDatabase.Refresh() and AssetDatabase.Import()
The issue only occurs when the second argument of the StreamWriter is set to 'false'
The issue only occurs when the scene is being selected
The issue always occurs with Lighting Settings and Animation Parameter windows open