uni-app小程序启动报错

TypeError: Cannot read property 'height' of null

   at Object.<anonymous> (index.vue:356)

   at Function.<anonymous> (WAServiceMainContext.js?t=wechat&s=1753437192620&v=3.8.12:1)

   at :38694/appservice/<SelectorQuery callback function>

   at WAServiceMainContext.js?t=wechat&s=1753437192620&v=3.8.12:1

   at WAServiceMainContext.js?t=wechat&s=1753437192620&v=3.8.12:1

   at Array.forEach (<anonymous>)

   at WAServiceMainContext.js?t=wechat&s=1753437192620&v=3.8.12:1

   at WAServiceMainContext.js?t=wechat&s=1753437192620&v=3.8.12:1

   at WASubContext.js?t=wechat&s=1753437192620&v=3.8.12:1

   at pe (WASubContext.js?t=wechat&s=1753437192620&v=3.8.12:1)

代码如下：

let self = this

// #ifdef MP

// 获取小程序头部高度

this.navH = app.globalData.navHeight;

let info = uni.createSelectorQuery().select(".mp-header");

info.boundingClientRect(function(data) {

self.marTop = data.height

self.poTop = Number(data.height) + 84

}).exec()

// #endif