Steps to repro:

1. Download the repro project and open it;
2. Go to Project Settings (Edit>Project Settings...);
3. Select Editor tab in the Project Settings window;
4. Expand Mode dropdown list under the Asset Pipeline (experimental) section;
5. Select 'Version 2' in the Mode dropdown list.

Actual result:
`SerializedObject target has been destroyed.
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)` error is shown. See attached video.

Expected result:
No errors are shown after switching Asset pipeline version.

Notes:
- On 2019.2.0a14, This bug occurs on selecting any dropdown from Edit > Project Settings > Editor
- Reproducible in 2019.2.0a10;
- In 2019.1.0b9 a different error is shown:
"Failed to load '/Users/vladimir/Documents/Unity Projects/LabsClCrash191/LabsShadowmask/Assets/Scenes/TheLabs_Shadowmask/LightingData.asset' because it was serialized with a newer version of Unity. (Has a higher SerializedFile version)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)"
- Reproducible on OSX 10.14.4 in the attached project and on Windows on the Lighting FTP project from Collab;
- The issue might not reproduce steadily; if it doesn't repro - save the project and restart Editor after switching Asset pipeline version. Then repeat the initial repro steps.
- Another way to repro is to switch Editor visualizations or open Project settings window.

Note:
Also occurring on 2019.2.0a14