InvalidOperationException when using web component menu item bindings in sample app

[danroth27]

Repro steps:

• Run the FluentUIServerSample
• Browse to the web component bindings
• Try out the menu item bindings

Error in browser console:

Error: System.InvalidOperationException: There was an error parsing the event arguments. EventId: '9'.
 ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.AspNetCore.Components.Web.WebEventData.DeserializeChangeEventArgs(String eventArgsJson)
   at Microsoft.AspNetCore.Components.Web.WebEventData.ParseEventArgsJson(UInt64 eventHandlerId, String eventArgsType, String eventArgsJson)
   --- End of inner exception stack trace ---
   at Microsoft.AspNetCore.Components.Web.WebEventData.ParseEventArgsJson(UInt64 eventHandlerId, String eventArgsType, String eventArgsJson)
   at Microsoft.AspNetCore.Components.Web.WebEventData.Parse(WebEventDescriptor eventDescriptor, String eventArgsJson)
   at Microsoft.AspNetCore.Components.Server.Circuits.CircuitHost.DispatchEvent(String eventDescriptorJson, String eventArgsJson)