When UDP Client is generated and Unlink Project from Service Settings window causes the editor to throw NullReferenceException, Refer attached video.

Steps to repro:
1. Create a new project.
2. Window > Package Manager > Unity Distribution Portal > Install
3. Edit > Project Settings > Service > Select organization
4. Unity Distribution Portal > Generate new UDP Client
5. Services > Unlink project

Actual Result:
NullReferenceException is thrown on Unliking the project from Services Settings window when UDP Client is already generated

Expected Result:
Project is Unlinked gracefully

Reproducible in:
2021.1.0a4, 2021.1.0a1, 2020.2.0b11 with package version 2.0.0

Working fine in:
2020.2.0b11, 2020.1.12f1 with package version 1.3.0, 1.2.0

Environment:
Windows10 and macOS 10.15

Stack trace:
NullReferenceException: Object reference not set to an instance of an object
UnityEngine.UDP.Editor.AppStoreProjectSettingsEditor.SetUpCannotGetProjectIdWindow () (at library/packagecache/com.unity.purchasing.udp@2.0.0/editor/appstoreprojectsettingseditor.cs:362)
UnityEngine.UDP.Editor.AppStoreProjectSettingsEditor.InitializeProperties () (at library/packagecache/com.unity.purchasing.udp@2.0.0/editor/appstoreprojectsettingseditor.cs:761)
UnityEngine.UDP.Editor.AppStoreProjectSettingsEditor.CheckUserState () (at library/packagecache/com.unity.purchasing.udp@2.0.0/editor/appstoreprojectsettingseditor.cs:430)
UnityEditor.EditorApplication.Internal_CallUpdateFunctions () (at <bd5493fc3cac4e0ca13e04a4b569b9a7>:0)