您在 Redux Observable 中预期流的位置提供了“undefined”

You provided `undefined` where a stream was expected in Redux Observable

尝试着手研究 RxJS 和 redux observable

我有这个:

export const getSomeData = (action$) =>
    action$.pipe(
        ofType(GET_USER_DATA),
        mergeMap((action) => getData(action.id)),
        map(fetchUserFulfilled),
        catchError((e) =>
            of({
                type: 'FAILED_TO_FETCH_DATA',
                e,
            }),
        ),
    )

效果很好,但现在我想在取回数据时实际触发 2 个 observable,所以我尝试了这个:

export const getSomeData = (action$) =>
    action$.pipe(
        ofType(GET_USER_DATA),
        mergeMap((action) => getData(action.id)),
        mergeMap((data) => {
            const newData = data.somethingelse
            of(fetchUserFulfilled(newData), anotherOne(newData))
        }),

        catchError((e) =>
            of({
                type: 'FAILED_TO_FETCH_DATA',
                e,
            }),
        ),
    )

但这是失败的。那么我该如何解决这个问题,我有什么误解,我应该如何正确使用 mergeMap

mergeMap 应该 return 一个可观察的

mergeMap((data) => {
            const newData = data.somethingelse
            return of(fetchUserFulfilled(newData), anotherOne(newData))
        }),