Handle scenario where an event handler was specified as the wrong type

[SteveSandersonMS]

Originally reported in #135

Currently if you declare an event handler with onsomeevent=@something, and @something isn't a UIEventHandler, then at runtime when the event is triggered, you will get There is no event handler with ID 0. This is because we only assign event handler IDs when the attribute value is the type we recognize (UIEventHandler).

Options:

• Handle it at compile time. Helpers like @onclick(...) cover this already, because they are defined to accept a UIEventHandler, and the compiler will automatically create one of those for you if you try to pass a compatible Action<UIEventArgs> or similar. Or we could have tag helper-type infrastructure that limits what values you can give for all attributes whose names correspond to known HTML events.
• Handle it better at runtime. If you try to raise an event and the corresponding handler attribute didn't have an event handler ID, report something like Cannot trigger event handler for {eventname} because is not of the correct type. Event handlers must be of type UIEventHandler; you supplied {othertype}.

[ghost]

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[mkArtakMSFT]

Hi. Thanks for contacting us.
We're closing this issue as there was not much community interest in this ask for quite a while now.
You can learn more about our triage process and how we handle issues by reading our Triage Process writeup.