run yarn && yarn webpack
open indexA.html
in chrome, open devtools console, you'll see an error, because "buildin/global.js" is being included in vendor-scripts which is not loaded on indexA.html
page, page B works well
you can try and add react into the vendor-scripts like this
"vendor-scripts": [
"react",
"mobx",
],
and now "process/browser.js" gone from a.js as well, it is tho required to load module "js-htmlencode" which is taken as example.