On adding "Screen Space Reflection" and "Ambient Occlusion" Override to "Volume Profile" asset throws NullReferenceException continuously when Scriptable Render Pipeline Settings is set to "None" also "Add Override button disappears, refer the attached video.

Steps to repro:
1. Create a new project with HDRP Template
2. Upgrade High Definition RP Package to 7.1.7
3. Edit > Project Settings > Graphics > Scriptable Render Pipeline Settings > None
4. Assets > Create > Volume Profile
5. Select "New Volume Profile in the Project Window
6. Inspector > Add Override > Lighting > Screen Space Reflection/AmbientOclusion

Actual Result:
NullReferenceException is thrown continuously on adding "Lighting" Override to "New Volume Profile" asset and the "Add Override" button disappears.

Expected Result:
Screen Space Reflection override attached to Volume Profile Assets without any exception being thrown and the "Add Override" button appears.
Suggestion: Instead of exceptions it will show the Scriptable Pipeline is not assigned.

Reproducible on:
2020.1.0a20, 2019.3.0f6, 2019.3.0b4 with package version 7.1.7, 7.1.5

Working fine on:
2020.1.0a1, 2019.3.0b4 with package version 7.1.2

Package Found version: 7.1.7, 7.1.6, 7.1.5
Package Working fine version: 7.1.2, 7.1.1

Environment:
Windows 10 & macOS 10.14

Workaround:
Assigned Scriptable Render Pipeline in the Graphics Settings

Stack trace:
NullReferenceException: Object reference not set to an instance of an object
UnityEditor.Rendering.HighDefinition.HDScreenSpaceReflectionEditor.OnInspectorGUI () (at Library/PackageCache/com.unity.render-pipelines.high-definition@7.1.7/Editor/Lighting/Reflection/HDScreenSpaceReflectionEditor.cs:86)
UnityEditor.Rendering.VolumeComponentEditor.OnInternalInspectorGUI () (at Library/PackageCache/com.unity.render-pipelines.core@7.1.7/Editor/Volume/VolumeComponentEditor.cs:225)
UnityEditor.Rendering.VolumeComponentListEditor.OnGUI () (at Library/PackageCache/com.unity.render-pipelines.core@7.1.7/Editor/Volume/VolumeComponentListEditor.cs:225)
UnityEditor.Rendering.VolumeProfileEditor.OnInspectorGUI () (at Library/PackageCache/com.unity.render-pipelines.core@7.1.7/Editor/Volume/VolumeProfileEditor.cs:25)
UnityEditor.UIElements.InspectorElement+<>c__DisplayClass58_0.<CreateIMGUIInspectorFromEditor>b__0 () (at <bba5ae680bc14113ade3be5cc43cbed6>:0)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)