Option vs vanilla strict null checking

a.rb

(() => {
    const f = (c: number): Option<number> => c === 2 ? Some(c) : None
    const add1 = (c: number): number => c + 1;
    const maybeNumber = Option(1)
    maybeNumber.flatMap(f).map(add1).getOrElse(5)
})()

(() => {
    const f = (c: number): number | undefined => c === 2 ? c : undefined;
    const add1 = (c: number): number => c + 1;
    const maybeNumber: number | undefined = 1;
    // flatMap
    const a: number | undefined = maybeNumber !== undefined ? f(maybeNumber) : undefined;
    // map
    const b: number | undefined = a !== undefined ? add1(a) : undefined;
    // getOrElse
    const c: number = b !== undefined ? b : 5;
})()