Errors from methods returning a Promise are not bubbling up when Promise is converted to Observable

In order to achieve consistency, i want to convert methods returning Promises to Observable.
However, errors are ignored when trying to catch the error either from the method or from the caller of the method.

See the code below.

```typescript
createList(newList: NewListDTO) {
const collectionRef = collection(this.db, `lists`);

const newListDoc = addDoc(collectionRef, {
name: newList.name,
uid: newList.uid,
created_at: serverTimestamp(),
});

// return defer(async () => {
// return await newListDoc;
// });

return scheduled(newListDoc, asyncScheduler).pipe(
// FIXME: error is not being caught from firstore addDoc
catchError((err) => {
return throwError(() => err);
}),
);
}
```

從 createList 範例開始，比較被註解的 defer(async ...) 方法與 scheduled(newListDoc, asyncScheduler) 及其 catchError 處理器。重現失敗的 addDoc 路徑，並檢查 Promise 中的錯誤是否同時到達該方法及其呼叫端。報告的 Firestore 錯誤能夠透過返回的 Observable 冒泡，即表示完成。

由索引模型根據 Issue 內容生成。