[Bug] StateView System.InvalidOperationException: Collection was modified; enumeration operation may not execute.

[ValonK]

Description

Im getting this Crash when using StateLayout like this

<Grid toolkit:StateLayout.CurrentState="{Binding CurrentState}"
      toolkit:StateLayout.AnimateStateChanges="True"
      toolkit:StateLayout.CurrentCustomStateKey="{Binding CustomStateKey}">
     <toolkit:StateLayout.StateViews>
        <toolkit:StateView StateKey="Loading">
            <states:LoadingStateView/>
        </toolkit:StateView>
        <toolkit:StateView StateKey="Custom" CustomStateKey="{x:Static helpers:StateKeys.NotAuthenticated}">
            <states:NotAuthenticatedStateView />
        </toolkit:StateView>
        <toolkit:StateView StateKey="Success">
            <ContentView Content="{StaticResource SuccessView}"/>
        </toolkit:StateView>
        <toolkit:StateView StateKey="Empty">
            <states:EmptyView  />
        </toolkit:StateView>
    </toolkit:StateLayout.StateViews>
</Grid>

internal async void OnRefreshAsync()
{
    if (!IsAuthenticated)
    {
        return;
    }

    CurrentState = LayoutState.Loading;
    try
    {
        await LoadItems();
    }
    finally
    }
        CurrentState = LayoutState.Success;
    }
}

android.runtime.JavaProxyThrowable: System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
at System.Collections.Generic.List`1+Enumerator[T].MoveNextRare () [0x00013] in <9e65554b56364c219ee375864f4fd8c4>:0 
at System.Collections.Generic.List`1+Enumerator[T].MoveNext () [0x0004a] in <9e65554b56364c219ee375864f4fd8c4>:0 
at System.Linq.Enumerable+WhereEnumerableIterator`1[TSource].MoveNext () [0x0004e] in <b943f5a0a8474cebaa297e667e2095bb>:0 
at System.Linq.Enumerable+<OfTypeIterator>d__32`1[TResult].MoveNext () [0x00067] in <b943f5a0a8474cebaa297e667e2095bb>:0 
at System.Linq.Enumerable+SelectIListIterator`2[TSource,TResult].MoveNext () [0x00029] in <b943f5a0a8474cebaa297e667e2095bb>:0 
 at System.Threading.Tasks.Task.WhenAll[TResult] (System.Collections.Generic.IEnumerable`1[T] tasks) [0x000ba] in <9e65554b56364c219ee375864f4fd8c4>:0 
 at Xamarin.CommunityToolkit.UI.Views.StateLayoutController.ChildrenFadeTo (Xamarin.Forms.Layout`1[T] layout, System.Boolean animate, System.Boolean isHide) [0x000ae] in <d695d744715f441683440b16d4c7616b>:0 
 at Xamarin.CommunityToolkit.UI.Views.StateLayoutController.SwitchToTemplate (Xamarin.CommunityToolkit.UI.Views.LayoutState state, System.String customState, System.Boolean animate) [0x003b8] in <d695d744715f441683440b16d4c7616b>:0 
 at System.Runtime.CompilerServices.AsyncMethodBuilderCore+<>c.<ThrowAsync>b__7_0 (System.Object state) [0x00000] in <9e65554b56364c219ee375864f4fd8c4>:0 
  at Android.App.SyncContext+<>c__DisplayClass2_0.<Post>b__0 () [0x00000] in <ab7a92db3c6e45c6ae5846565187cb8b>:0 
at Java.Lang.Thread+RunnableImplementor.Run () [0x00008] in <ab7a92db3c6e45c6ae5846565187cb8b>:0 
at Java.Lang.IRunnableInvoker.n_Run (System.IntPtr jnienv, System.IntPtr native__this) [0x00008] in <ab7a92db3c6e45c6ae5846565187cb8b>:0 
 at (wrapper dynamic-method) Android.Runtime.DynamicMethodNameCounter.27(intptr,intptr)

• Version with issue:
• Last known good version:
• IDE:
• Platform Target Frameworks: 11
• iOS: 12
• Android: 11

[AndreiMisiukevich]

@ValonK https://github.com/xamarin/XamarinCommunityToolkit/issues/784

https://github.com/xamarin/XamarinCommunityToolkit/issues/784#issuecomment-768207140

[jfversluis]

So, this is not a bug? Or what is going on with this one?

[AndreiMisiukevich]

@ValonK can you reproduce this issue on the latest nuget version? If yes, then please attach a sample project. Thanks!