Number.isFinite is missing type guard

[Juraj-Masiar]

Bug Report

The Number.isFinite accepts unknown parameter and returns true only if the parameter is Number.
So there should be a type guard saying it's a Number.
MDN:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isFinite

🔎 Search Terms

Number.isFinite

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about Number.isFinite

⏯ Playground Link

Playground link with relevant code

💻 Code

function double(x: number | undefined): number {
  if (Number.isFinite(x)) {
    return x * 2;  // ERROR: Object is possibly 'undefined'.
  }
  return 0;
}

🙁 Actual behavior

ERROR: Object is possibly 'undefined'.

🙂 Expected behavior

No error :)

[MartinJohns]

Duplicate of #39090. Found using the search terms you provided in your issue. This has been rejected with a fairly good reason already.