Steps to reproduce:
# Install the 1.7.0 Asset Manager version
# Open "Asset Manager" (Window -> Asset Manager) and check that data is displayed in the Asset Manager window
# Go to the Package Manager window and select the "Asset Manager" package
# In the "Version History" tab, select the older version
# Please install it 
# Open "Asset Manager" (Window -> Asset Manager) and check that data is displayed in the Asset Manager window
# Go to the Package Manager window and select the "Asset Manager" package one more time
# This time, select the latest version and update it again
# Open the Asset Manager window and observe the result
# If it is needed, repeat steps 3, 4, 5, and 6 several times with different Asset Manager versions and observe the result

Actual results: The Asset Manager window is empty. Console displays errors

Expected results: No errors in the Console window, and the Asset Manager window should always present data

Reproducible with versions: 1.7.0(6000.0.58f1, 6000.2.3f1, 6000.3.0b2)

Can’t test with versions: 

Tested on (OS): macOS - Sequoia 15.6.1

Notes: An error from the Console:

NullReferenceException: Object reference not set to an instance of an object
Unity.AssetManager.UI.Editor.PageManager.OnEnable () (at ./Library/PackageCache/com.unity.asset-manager-for-unity@a7a57dade898/Editor/UI/Services/PageManager.cs:134)
Unity.AssetManager.Core.Editor.BaseService.set_Enabled (System.Boolean value) (at ./Library/PackageCache/com.unity.asset-manager-for-unity@a7a57dade898/Editor/Core/Services/ServicesContainer.cs:32)
Unity.AssetManager.Core.Editor.ServicesContainer.EnableService (Unity.AssetManager.Core.Editor.IService service, System.Collections.Generic.Queue`1[T] serviceEnablingQueue) (at ./Library/PackageCache/com.unity.asset-manager-for-unity@a7a57dade898/Editor/Core/Services/ServicesContainer.cs:273)
Unity.AssetManager.Core.Editor.ServicesContainer.Resolve[T] () (at ./Library/PackageCache/com.unity.asset-manager-for-unity@a7a57dade898/Editor/Core/Services/ServicesContainer.cs:254)
Unity.AssetManager.UI.Editor.AssetManagerWindow.MenuEntry () (at ./Library/PackageCache/com.unity.asset-manager-for-unity@a7a57dade898/Editor/UI/UIElements/AssetManagerWindow.cs:27)