Race condition with SetIsLoading on Windows

[craigwi]

I hit a race condition during startup on Windows which can result in the following exception:

System.ArgumentException: An item with the same key has already been added. Key: Microsoft.Maui.Controls.BindableProperty
at System.Collections.Generic.Dictionary2.TryInsert(TKey key, TValue value, InsertionBehavior behavior) at System.Collections.Generic.Dictionary2.Add(TKey key, TValue value)
at Microsoft.Maui.Controls.BindableObject.SetValueCore(BindableProperty property, Object value, SetValueFlags attributes, SetValuePrivateFlags privateAttributes, SetterSpecificity specificity)
at Microsoft.Maui.Controls.BindableObject.SetValue(BindablePropertyKey propertyKey, Object value)
at FFImageLoading.Maui.CachedImage.SetIsLoading(Boolean isLoading)
at FFImageLoading.Maui.Platform.CachedImageHandler.UpdateImage(Image imageView, CachedImage image, CachedImage previousImage)
at System.Threading.Tasks.Task.<>c.b__128_0(Object state)
at Microsoft.UI.Dispatching.DispatcherQueueSynchronizationContext.<>c__DisplayClass2_0.b__0()

This appears to be due to two threads trying to add the IsLoading property at the same time. I thought it was the MainThreadDispatcher which gets the Dispatcher based on the current thread, not specifically the main thread. I created a private version of MainThreadDispatcher which always used Application.Current.Dispatcher, but that did not help.

Given the core issue of two threads adding the same property to the dictionary, I tried to force that property entry to be added. That seems to work.

Specifically, I created this:

public class CachedImage2 : CachedImage
{
    public CachedImage2()
    {
        // preset so as not to hit a race condition later
        this.SetIsLoading(false);
    }
}

and then always used CachedImage2.

[juanmalm]

I'm facing same issue on a .NET MAUI project using .NET 9 and targeting Windows platform