When a newly created Prefab.index searched in the Quick search window of which properties were changed and saved earlier and then deleting it causes continuous "SerializedObject target has been destroyed." errors thrown in the console.

Steps to repro:
1. Create a New Project
2. Click on Search Icon besides collab Icon
3. Enter "Index" in the Global Search window
4. Select Prefab Index and Close the Search window and open it again
5. Assets.Index > Open > Change Option Property > Save.
6. Project Window > Assets > Delete

Actual Result:
"SerializedObject target has been destroyed." errors are thrown continuously in the console.

Expected Result:
No errors should be thrown in the console.

Workaround:
Close and reopen the Search window.

Stacktrace:
SerializedObject target has been destroyed.
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&)

Reproducible in:
2021.1.0a2, 2021.1.0a1.

Environment:
Occurring on Windows 10 & macOS 10.15.

Note: 1. Global Search option in the Editor is introduced in 2021.1.0a1
2. Unable to check on 2021.1.0a1 because of this bug ID [1283926]