Type Alias Tail2TypesOrUndefined<T, U>

Tail2TypesOrUndefined: T extends []
    ? U
    : T extends [unknown]
        ? U
        : T extends [unknown, unknown] ? U : Tail<Tail<T>>[number]

Returns the union of types in an array, but the first and the second one, uses U as a fallback if the array is empty.