dispatch allows for optional details, but the corresponding events doesn't account for that

[kenteramin]

Hello there!

I've noticed that dispatch that we get by typing createEventDispatcher<{ something: string }> will allow to dispatch the event with undefined whereas on the handler on:something={event => {}} the event type won't be optional event: CustomEvent<string>.

Is it intentional? Can I do something about it? It creates quite some grief for me :))