IInvocationBinder throws or returns empty array inconsistently

[AArnott]

In writing my own IHubProtocol implementation, I found that when a method is invoked, there is no good way to determine whether a method exists with the target name to invoke. As a result, I get unhelpful exceptions thrown.

In particular, while deserializing the invocation request I need the parameter types. I call IInvocationBinder.GetParameterTypes passing in the name of the target method that I have already deserialized. When the method does not exist, it simply returns an empty array, causing my BindArguments method to throw because the number of arguments and the number of parameters mismatch. But that's a red herring. The real issue is that the method itself does not exist at all.

I notice that IInvocationBinder.GetReturnType does throw when the target method does not exist.

Why the two diverging and undocumented policies for these two methods?

What is the best way to handle this?

aspnetcore/src/SignalR/clients/csharp/Client.Core/src/HubConnection.cs

Lines 2395 to 2423 in 4069504

	Type IInvocationBinder.GetReturnType(string invocationId)
	{
	if (!TryGetInvocation(invocationId, out var irq))
	{
	Log.ReceivedUnexpectedResponse(_logger, invocationId);
	throw new KeyNotFoundException($"No invocation with id '{invocationId}' could be found.");
	}
	return irq.ResultType;
	}
	Type IInvocationBinder.GetStreamItemType(string invocationId)
	{
	// previously, streaming was only server->client, and used GetReturnType for StreamItems
	// literally the same code as the above method
	if (!TryGetInvocation(invocationId, out var irq))
	{
	Log.ReceivedUnexpectedResponse(_logger, invocationId);
	throw new KeyNotFoundException($"No invocation with id '{invocationId}' could be found.");
	}
	return irq.ResultType;
	}
	IReadOnlyList<Type> IInvocationBinder.GetParameterTypes(string methodName)
	{
	if (!_hubConnection._handlers.TryGetValue(methodName, out var invocationHandlerList))
	{
	Log.MissingHandler(_logger, methodName);
	return Type.EmptyTypes;
	}