uniCloud云对象调用返回undefined

调试 console都正常，但是return后，客户端调用的就是获取不到

客户端代码：

async getToken() {  
                const wenxinObj = uniCloud.importObject('aio-wenxin')  
                try {  
                    const res = await wenxinObj.getWenxinToken()  
                    console.log('page callapi token =', res)  
                    if(res.errCode==0) {  
                        this.accessToken = res.data  
                    }  
                } catch (e) {  
                    console.log(e.errCode)  
                    console.log(e.errMsg)  
                }  
            },

云对象代码：

async function getWenxinToken() {  
    let result = null  
    const db = uniCloud.database();  
    try {  
        let res = await db.collection('token').where({  
            _id: '63874807f43e6046ed553b2b'  
        }).get({  
            getOne: true  
        })  
        let token = res.data[0].astoken  
        console.log('getWenxinToken res = ', res, token)  
        result = {  
            errCode: 0,  
            errMsg: '成功',  
            data: token  
        }  
    } catch (e) {  
        console.log('get wenxintoken error = ', e)  
        result = {  
            errCode: -1,  
            errMsg: '查询失败'  
        }  
    }  
    return result  
}