【报Bug】项目升级到VUE3后getSystemInfoSync不能用了

操作步骤：

1、新建一个uni-app 的项目，使用默认模板
2、在配置中把VUE版本选择为3
3、在APP.vue 的onLaunch 方法内，添加了语句 let isIos = uni.getSystemInfoSync().platform == 'ios';

预期结果：

正常结果

实际结果：

在控制台报错
VM313:5 app.js错误:
TypeError: Cannot read property 'getSystemInfoSync' of undefined
at initLocale (uni.mp.esm.js?97ff:571)
at parseApp (uni.mp.esm.js?97ff:552)
at createApp (uni.mp.esm.js?97ff:567)
at Object.mount (vue.runtime.esm.js?dc04:4890)
at Object.<anonymous> (main.js? [sm]:21)
at __webpack_require__ (null:81)
at checkDeferredModules (null:47)
at Array.webpackJsonpCallback [as push] (null:34)
at main.js:4
at p (VM280 WAService.js:2)(env: macOS,mp,1.05.2110110; lib: 2.20.0)

TypeError: Cannot read property 'getSystemInfoSync' of undefined
at initLocale (uni.mp.esm.js?97ff:571)
at parseApp (uni.mp.esm.js?97ff:552)
at createApp (uni.mp.esm.js?97ff:567)
at Object.mount (vue.runtime.esm.js?dc04:4890)
at Object.<anonymous> (main.js? [sm]:21)
at __webpack_require__ (null:81)
at checkDeferredModules (null:47)
at Array.webpackJsonpCallback [as push] (null:34)
at main.js:4
at p (VM280 WAService.js:2)(env: macOS,mp,1.05.2110110; lib: 2.20.0)

TypeError: Cannot read property 'getSystemInfoSync' of undefined
at initLocale (uni.mp.esm.js?97ff:571)
at parseApp (uni.mp.esm.js?97ff:552)
at createApp (uni.mp.esm.js?97ff:567)
at Object.mount (vue.runtime.esm.js?dc04:4890)
at Object.<anonymous> (main.js? [sm]:21)
at __webpack_require__ (null:81)
at checkDeferredModules (null:47)
at Array.webpackJsonpCallback [as push] (null:34)
at main.js:4
at p (VM280 WAService.js:2)(env: macOS,mp,1.05.2110110; lib: 2.20.0)