Destructuring a possibly `undefined` object not caught, throws an error at runtime

bengry commented 1 month ago

destructuring, Cannot destructure as it is undefined, optional chaining destructuring

This changed between versions __ and ___
This changed in commit or PR ___
This is the behavior in every version I tried, and I reviewed the FAQ for entries about _____
I was unable to test this on prior versions because ___

const input: {
    a?: { b?: { c: string } }
} = { a: undefined }

const { ...b } = input.a?.b

No error reported by TypeScript.

TypeScript should have an indicative error, since this expression might result in undefined, which cannot be destructured.

Similar to this:

Rest types may only be created from object types.(2700)

The error in the JavaScript being ran is:

Uncaught TypeError: Cannot destructure '(intermediate value)' as it is undefined.

MartinJohns commented 1 month ago

@Andarist Does your PR #60121 fix this as well?

Andarist commented 1 month ago

microsoft / TypeScript