Datagrid: GroupBy does not work in combination with QueryBy

[jens-cailliau]

warn: Microsoft.AspNetCore.Components.Server.Circuits.RemoteRenderer[100]
      Unhandled exception rendering component: Object reference not set to an instance of an object.
      System.NullReferenceException: Object reference not set to an instance of an object.
         at Blazority.Internal.DatagridContext`1.GroupItemCount(String key)
         at Blazority.Datagrid`1.<BuildRenderTree>b__0_0(RenderTreeBuilder __builder2)
         at Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder.AddContent(Int32 sequence, RenderFragment fragment)
         at Microsoft.AspNetCore.Components.CascadingValue`1.Render(RenderTreeBuilder builder)
         at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment, Exception& renderFragmentException)

To Reproduce
Add DataGrid with QueryBy And GroupBy Parameter.

Environment

• Blazority Version [0.10]
• .NET Core Version [5.0]
• Browser [chrome]