Incorrect type when spreading two Sets to an object

[styfle]

Bug Report

I had a typo where I used curly brackets instead of square brackets to spread to Set variables, but TypeScript didn't catch the error at build time. Instead, the code failed at runtime.

🔎 Search Terms

set, object, spread

🕗 Version & Regression Information

• This is the behavior in every version I tried back to TS 3.x

⏯ Playground Link

Playground link with relevant code

💻 Code

const first = new Set(['one'])
const second = new Set(['two'])
const all = { ...first, ...second };
console.log(all) // prints `{}`
all.add('wat') // TS is happy but JS throws a runtime error

🙁 Actual behavior

TS thinks the Set methods like .add() and .clear() are available and doesn't show a build error for the last line.

🙂 Expected behavior

TS should show an error at build time to reflect actual JS usage at runtime: no Set method are available for the last line.

[nmain]

I believe this is a duplicate of #9726

[styfle]

Yep, looks like a very similar to #33081 which is a duplicate of #9726