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

🔎 Search Terms

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

🕗 Version & Regression Information

• 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 _______

⏯ Playground Link

https://www.typescriptlang.org/play/?ts=5.6.2#code/MYewdgzgLgBAlmADgVygLhgbwLACgYEwCGA-BpjAEZlYzAbQBOCA5jAL4d6cC8tRGZGAAmAUwBmCUcK648oSLAoA6VZQ4w+CFFGWlllIA

💻 Code

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

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

🙁 Actual behavior

No error reported by TypeScript.

🙂 Expected behavior

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)

Additional information about the issue

The error in the JavaScript being ran is:

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

Bắt đầu với liên kết TypeScript 5.6.2 Playground và ví dụ destructuring có liên quan đến input.a?.b. Theo dõi cách checker xử lý một đối tượng có thể là undefined trong một biểu thức object-rest destructuring, sau đó xác minh rằng hành vi hoàn thiện báo một diagnostic mang tính chỉ dẫn thay vì cho phép mã gây ra lỗi khi chạy.