TypeScript unchecked index access

Question

Why does TypeScript think an object in an array is possibly undefined when noUncheckedIndexedAccess configuration is enabled even after the length is checked?

Playground

interface Item {
    x: number
}

declare var items: Item[]

if(items.length === 2) { // Length is checked
    const [first, second] = items

    first.x // Error: Object is possibly undefined
    second.x // Error: Object is possibly undefined
}

I would expect the length === 2 to "prove" to TypeScript that the object in the first and second position of the array are present.