Initial value when typing Template Refs

[FloEdelmann]

In TypeScript with Composition API → Typing Template Refs, it is recommended to use an explicit initial value of null:

const el = ref<HTMLInputElement | null>(null) // type: Ref<HTMLInputElement | null>

Why not simplify it to leverage the implicit undefined instead?

const el = ref<HTMLInputElement>() // type: Ref<HTMLInputElement | undefined>