Updating volar from 1.2 to 1.4 breaks prop typing for events

[Fuzzyma]

Since using v 1.4 of volar, I get strange errors on event handlers that might be undefined:

The handling function might be undefined and that seems to be a problem all of a sudden.
Before, undefined as event handler would just not bind to that event.

I think this error is triggered when declaring props instead of events (e.g. onCancel prop vs cancel emit).
But it also happens for the transition component so I am not entirely sure

[johnsoncodehk]

Transition @after-leave type not work as well even in v1.2.0, which shows unknown in v1.2.0, but it should be Hook<(el: Element) => void>. Fixed in 09fbbb7.