Const typeguard flows into methods but not properties

[jods4]

Bug Report

🔎 Search Terms

type guard get property const

🕗 Version & Regression Information

Fails at least on 4.3.5 and 4.4.0-beta.

• I was unable to test this on prior versions because I noticed this behavior very recently.

⏯ Playground Link

Playground link with relevant code

💻 Code

const x: string | number = Math.random() < 0.5 ? "str" : 123;
if (typeof x === "string") {
  let obj = {
    get prop() { return x.toUpperCase() },  // Error: property toUpperCase doesn't exist on number
    method() { return x.toUpperCase() } // Ok
  }
}

🙁 Actual behavior

The method compiles, the getter raises an error.

🙂 Expected behavior

Behaviour should be the same for both.
Given that x is a const and its type was narrowed to string, no error seems right.

[softwareCobbler]

should control flow flow into setters, too?

[jods4]

@softwareCobbler Yes.

const x: string | null = "abc";
if (x) {
 const obj = {
    // Following is valid and should not warn that x might be null
    set test(val) { console.log(x.toUpperCase(); }
  }
}