Whenever an event is raised that causes a targetInvocationException, EventBrokerHandlerBase.cs throws a null object exception due to the ExtensionHost property being null. This occurs when using an instance of the derived class, UserInterface.
In UserInterface.cs, the method
public virtual void Initialize(object subscriber, MethodInfo handlerMethod, IExtensionHost extensionHost)
is overridden but the base method, which sets the this.ExtensionHost property, is never called.
The extensionHost argument is passed into the UserInterface.cs and is not null.
This issue appears to affect the UserInterface and UserInterfaceAsync classes.