明明只读为什么会报不能修改的错误？报错：TypeError: Cannot assign to read only property '0' of string 'article_id'

const userActionsRes = await db.collection(table_name)
.where({
user_id: userId,
action_type: {
$in: ['like', 'collect']
}
})
.field('article_id').get();//读取当前用户点赞收藏的文章id