[MVVM] Using ObservableCollection with CollectionView IsGrouped="True" causes crash

[megukaphii]

Describe the bug

When using a CollectionView where the ItemSource is set to a binding of type ObservableCollection, and IsGrouped is set to True, the app crashes if the ObservableCollection is updated such that: there are more than 2 items in the first group, or there is more than 1 item in any subsequent group.

I tested this by copy+pasting from Microsoft's official CollectionView grouping docs in a brand new project: https://learn.microsoft.com/en-us/dotnet/maui/user-interface/controls/collectionview/grouping Please find said project here: https://github.com/megukaphii/GroupedCollectionViewBug

Regression

No response

Steps to reproduce

1. Download the repo linked above: https://github.com/megukaphii/GroupedCollectionViewBug
2. Run the project on Windows and click the "Load Animals" button
3. Note that the program does not crash with only 1 animal in the second "Monkeys" group, and that it does crash if you subsequently add a third animal to the "Bears" group

Expected behavior

The app does not crash.

Screenshots

No response

IDE and version

Rider

IDE version

RD-233.11361.12

Nuget packages

• [ ] CommunityToolkit.Common
• [ ] CommunityToolkit.Diagnostics
• [ ] CommunityToolkit.HighPerformance
• [X] CommunityToolkit.Mvvm (aka MVVM Toolkit)

Nuget package version(s)

8.2.2

Additional context

No response

Help us help you

No, just wanted to report this

[megukaphii]

Sorry, I'm using the CommunityToolkit and missed that the ObservableCollection isn't actually part of it! Please ignore this.