Fs-extra only work in backend module?

I have used theia version1.32.0 before today, and I want to update to the new version. I download newer blueprint and tried my code. the blueprint now uses v1.37.0, I got error as follow

I find that fs-extra work correctly in the backend module, the build is ok

I try to add fs-extra to the frontend module, build gets error as above

This is very strange because fs-extra work correctly both in frontend and backend when I use theia version 1.32.0. fs-extra can only be used in the backend for newer version?

Uhm, fs-extra cannot work in the frontend. The frontend doesn’t have access to the local file system, and cannot be packaged into a bundled browser application. Which is exactly the error you’re seeing in the console. Maybe an older version of webpack included a polyfill, but that only stubbed the node.js API.

Anyway, all file system access in Theia is supposed to go through the FileService API.