-Assertion failed errors are thrown on removing compositor from the scene.
-Assertion failed errors are thrown continuously on changing the resolution value to Half.

Steps to repro:
1. Create a new HDRP template project
2. Windows > Render Pipeline > Graphics Compositor.
3. Enable Compositor > Render Schedule > Base Layer.
4. Properties > AOVS > Albedo.
5. Properties > AOVS > None.
6. Properties > Resolution > Half.
7. Uncheck Enable Compositor > Click on Remove compositor from scene.

Actual Result:
Assertion failed errors are thrown in the console.

Expected Result:
No errors in the console.

Reproducible in:
2020.2.0a20 with Package version 10.0.0-preview.27.

Working Fine in:
2020.2.0a20 with Package version 9.0.0-preview.33.

Note:
-HDRP Compositor window introduced in 9.0.0 preview.33.
-Package Version 10.0.0 preview.27. is available only in 2020.2.0a20.

Environment:
Occurring on Windows 10 & Mac 10.15.

Stacktrace:
Assertion failed
UnityEditor.EditorGUI/PopupCallbackInfo:SetEnumValueDelegate (object,string[],int)

Assertion failed
UnityEngine.GUIUtility:ProcessEvent(int,intptr,bool&)