What problem does this feature solve?

If the E in FunctionalComponent<P, E> is EmitsOptions, and the E in defineEmits() is EmitsOption, why do they have different shapes?

E in FunctionalComponent<P, E> has to be { "event-name": (param: Param) => void }

E in defineEmits() has to be { (event: "event-name", param: Param): void }

What does the proposed API look like?

{ "event-name": (param: Param) => void }

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