[Bug] BlazoredToast.OnInitializedAsync null reference exception in 4.2.0

[rramer-web-com]

In 4.2.0, Settings.ShowProgressBar is null in BlazoredToast.OnInitializedAsync when using a ToastService.ShowToast method without explicitly providing optional settings that override ShowProgressBar.

ex. _toastService.ShowToast<Alert>(toastParameters);

This leads to the following runtime error:

Error: System.InvalidOperationException: Nullable object must have a value.
   at System.Nullable`1.get_Value()
   at Blazored.Toast.BlazoredToast.OnInitializedAsync()
   at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()

It looks like the breaking changes were in the following commit which changed ShowProgressBar from bool to bool?

Fix settings to allow instance settings to override global settings (https://github.com/Blazored/Toast/pull/226)

BlazoredToasts.BuildCustomToastSettings(Action<ToastSettings>? settings) might need to define a sensible default.