Steps to reproduce:
1. Create a new project
2. Upgrade to HDRP 7.0.1
3. Open Render Pipeline Wizard
4. Upgrade to HDRP 7.1.2
5. Notice that the wizard window is broken now with the following errors in the console window:
NullReferenceException: Object reference not set to an instance of an object
UnityEditor.Rendering.HighDefinition.HDWizard.OnGUI () (at Library/PackageCache/com.unity.render-pipelines.high-definition@7.1.2/Editor/DefaultScene/HDWizard.Window.cs:122)
System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters,
...

Reproduced in: 2020.1.0a6, 2019.3.0b5
HDRP package reproduced in: 7.1.2

Expected result: render pipeline wizard window should be refreshed after updating package

Workaround: reopen render pipeline window or restore layout by Window -> Render Pipeline -> HD Render Pipeline Wizard