关于_inc(值) 数据库自增 这个里面的值不能用变量吗？

js:
 check(){
        const dc = db.command
                db.collection('ruku').where({
                goods_name:this.data.goodList,
                store:this.data.storeList
        }).get().then(res=>{
            console.log(res)
            db.collection('ruku').doc(res.data[0]._id).update({
                data:{
                    goods_num:dc.inc(this.data.count)
                },
                
            }).then(ress=>{
                console.log(ress)
            })
        })
    },

控制台：Error: errCode: -502001 database request fail | errMsg: [FailedOperation] multiple write errors: [{write errors: [{Cannot increment with non-numeric argument: {goods_num: "15325"}}]}, {<nil>}]
    at new t (WASubContext.js?t=wechat&s=1650450834060&v=2.14.1:17)
    at Function.success (WASubContext.js?t=wechat&s=1650450834060&v=2.14.1:17)
    at d (WASubContext.js?t=wechat&s=1650450834060&v=2.14.1:2)
    at Object.success (WASubContext.js?t=wechat&s=1650450834060&v=2.14.1:2)
    at r (WASubContext.js?t=wechat&s=1650450834060&v=2.14.1:26)
    at WASubContext.js?t=wechat&s=1650450834060&v=2.14.1:26
    at b (WASubContext.js?t=wechat&s=1650450834060&v=2.14.1:26)
    at WASubContext.js?t=wechat&s=1650450834060&v=2.14.1:26
    at WAServiceMainContext.js:11
    at VM9 asdebug.js:1(env: Windows,mp,1.05.2203251; lib: 2.14.1)