How to reproduce:
1. Create a new 2018.3 Unity project
2. Add and dock a Project Settings window
3. Save the layout as a custom layout
4. Open the project in 2019.1 or 2019.2

Expected result: the layout works without any issues
Actual result: the layout gets corrupted

Reproducible with: 2019.1.0a12, 2019.1.0b3, 2019.2.0a4
Not reproducible with: 2019.1.0a11

Notes:
If the Project Settings window was inactive before saving the layout the Editor will load, but opening the Project Settings window will freeze that section of the Editor
If the Project Settings window was active before saving the layout the Editor will prompt with the 'Failed to load Layout' window. Any subsequent attempts to load the layout will cause this prompt to appear once more