On changing the "Asset Serialization Mode" from Editor Settings under Project Settings when preset of "Editor Settings" is created and focused in the Inspector then it causes Editor to throw NullReferenceException, Refer attached video.

Steps to repro:
1. Create a new project
2. Edit > Project Settings > Editor
3. Create preset of Editor Settings
4. Project window > EditorSetttings preset > Select
5. Project Settings > Editor > Asset Serialization > Change Mode
6. The open scene(s) have been modified externally > Reload

Actual Result:
NullReferenceException is thrown on changing "Asset Serialization Mode" and Reloading the scene from pop up when Editor Settings preset is focused in the Inspector

Expected Result:
Asset Serialization Mode get selected and the scene is reloaded gracefully

Occurring on:
2020.2.0a20

Working fine:
2020.2.0a19, 2020.1.1f1

Environment:
Windows10 and macOS 10.14

Stack Trace:
NullReferenceException: Object reference not set to an instance of an object
UnityEditor.UIElements.EditorElement.Reinit (System.Int32 editorIndex) (at <4a010c27075a4c2daedf3ee971af3236>:0)
UnityEditor.PropertyEditor.ProcessEditorElementsToRebuild (UnityEditor.Editor[] editors) (at <70c42c992fa442f8aa9edcf3e9f7b431>:0)
UnityEditor.PropertyEditor.DrawEditors (UnityEditor.Editor[] editors) (at <70c42c992fa442f8aa9edcf3e9f7b431>:0)
UnityEditor.PropertyEditor.RebuildContentsContainers () (at <70c42c992fa442f8aa9edcf3e9f7b431>:0)
UnityEditor.InspectorWindow.RedrawFromNative () (at <70c42c992fa442f8aa9edcf3e9f7b431>:0)
UnityEditor.GenericMenu:CatchMenu(Object, String[], Int32)