weex + weex UI : TypeError: _vm._px2rem is not a function

使用 weex 創(chuàng)建項目，引入 weex-ui，復(fù)制 weex-ui 的 demo 代碼，運行后瀏覽器控制臺報錯：

[Vue warn]: Property or method "_px2rem" is not defined on the instance but referenced during render. Make sure that this property is reactive, either in the data option, or for class-based components, by initializing the property. See: https://vuejs.org/v2/guide/reactivity.html#Declaring-Reactive-Properties.

found in

---> <WxcButton> at /Users/xuyuning/Sites/myApp/node_modules/weex-ui/packages/wxc-button/index.vue
       <HelloWorld> at /Users/xuyuning/Sites/myApp/src/components/HelloWorld.vue
         <Root>

看上去是 _px2rem 這個包調(diào)用失敗，而這個 WxcButton 是在 node_modules/ 中的，沒有修改權(quán)限。

有遇到類似問題的同學(xué)嗎？？求解！??！