Error from `exactOptionalPropertyTypes` not reported when using object spread with a ternary and optional property acces

まだ誰も着手していません。

### 🔎 Search Terms

exactOptionalPropertyTypes
object spread
ternary

### 🕗 Version & Regression Information

- This is the behavior in every version I tried, and I reviewed the FAQ for entries about exactOptionalPropertyTypes, object spread.

### ⏯ Playground Link

https://www.typescriptlang.org/play/?exactOptionalPropertyTypes=true&ts=5.9.3&ssl=5&ssc=32&pln=1&pc=1#code/C4TwDgpgBAYg9nKBeKBvAUFKYCGAnCAO2AEkATAfgC4oBnYPAS0IHN0BfddMiAYwBt80XnEL0oBAI4BXCPQBCcMiBrw4Abi78IwKMHwsdqhJvQB6M3QAWcAO60oEAB6RewCGUd48cPFDKyeogAok44bgDyYMCMojj8AAo+kHigACrgcuj6eIa6KKjYQsTkNFKyCkogAHS4BCWe7KYWUAC2jLS0zCxePn62VkRQ0l2sdGAEOJ44hJ7ueIT4INkGOshoUNVbABQMgRQbdUSkZGUQMnLAisq1xSdQ7FA0qOwAlA-qUC3yAKoA4lwRGJdIUjg0HutypdriBNDk8utCltqrs8PtDndSkV6vdHs83h8sF9LL8AeZLBBvL4oDgwJB8A4RN4+MB+CAoIwAGZQABu8UCHSghDguhw2GSlNANN4vDktA8UE5PlaNMIUDgACMAFYs9BA8Rgk4AJnWAHJTTSHPQmGMAD7DWYQTnMDxw1b5DbI1Ho0GY07Y47kE14tAEproIA

### 💻 Code

```ts
type Foo = {
parentId?: string
}

declare const requestBody: Foo;

let target: Foo;

// shows expected error due to ExactOptionalPropertyTypes
target = { parentId: requestBody.parentId };

// missing error when using spread and ternary
target = { ...(true ? { parentId: requestBody.parentId } : {}) }; // BUG

const { parentId } = requestBody;
target = { ...(true ? { parentId: parentId } : {}) }; // BUG

// error appears correctly if value is not a property accessed from an object
const parentId2 = '' as string | undefined;
target = { ...(true ? { parentId: parentId2 } : {}) };

```

### 🙁 Actual behavior

The expected error is silenced only in the specific case that combines object spread, ternary, and accessing an optional property from an object, although the types are always recognized correctly with `| undefined`.

### 🙂 Expected behavior

All scenarios demonstrated in the code snippet are expected to show the same error.

### Additional information about the issue

_No response_

リンクされた TypeScript Playground から始め、exactOptionalPropertyTypes の再現を実行します。直接代入、オブジェクトスプレッドの三項演算子、分割代入されたプロパティ、ローカル変数のケースを比較します。spread と ternary のケースが他のシナリオと同じ期待されるエラーを報告したら、issue は完了です。

索引モデルが issue の本文から書いたものです。