react-router-role-authorization | Role-based authorization components for React | Frontend Framework library

I don't see any mention of the fs module in your posted webpack setup. So, my guess is that your output application (app.js?) is trying to require and use fs. Webpack is building a client-side, front-end application, one that will be loaded in the browser; fs is not available in the browser.

(Double-check and make sure you aren't trying to, for example, read and write files on the user's machine using fs inside your client-side application. That is not possible in a browser-based application. For an intro to the concept of web applications with a front end and back end, check out the article React App With Node Backend.)