Ionic 2的代码在Ionic 5的环境下运行，提示如下错误:
ReferenceError: webpackJsonp is not defined at http://localhost:8100/build/main.js:1:1
查找资料发现是Ionic新版本的一些改变引起的，需要在Index.htm引入build/vendor.js
具体说明如下：
This is a breaking change in Ionic-App-Scripts
https://github.com/ionic-team/ionic-app-scripts/releases/tag/v2.0.0
src/index.html must be modified to include a new vendor script tag .
改成：
... <body> <!-- Ionic's root component and where the app will load --> <ion-app></ion-app> <script src="cordova.js"></script> <!-- The polyfills js is generated during the build process --> <script src="build/polyfills.js"></script> <!-- all code from node_modules directory is here --> <script src="build/vendor.js"></script> <!-- The bundle js is generated during the build process --> <script src="build/main.js"></script> </body> ...