[Bug]: React app is broken by `Upgrade npm packages`.

Environment

Coding platform: VS code
Coding platform version:

Version: 1.114.0
Commit: e7fb5e96c0730b9deb70b33781f98e2f35975036
Date: 2026-04-01T09:27:11Z (2 days ago)
Electron: 39.8.3
ElectronBuildId: 13658728
Chromium: 142.0.7444.265
Node.js: 22.22.1
V8: 14.2.231.22-electron.0
OS: Darwin arm64 24.6.0

Extension name: GitHub Copilot modernization
Extension version: 1.15.3
Language of your code: Front end react, back end Java
Selected model: Claude Sonnet 4.6 High
Operating System: Darwin arm64 24.6.0

How to Reproduce

I'm preparing my demo app for my JDConf. I used Copilot to do an analysis and select an appropriate app. My top choice is now at

https://github.com/edburns/dd-2844946-demo/tree/main/mehmetpekdemir-Todo-App .

See https://devdiv.visualstudio.com/DevDiv/_workitems/edit/2844935 for details on my process to arrive at this app.

I observe the app runs fine "out of the box" but is rendered unrunnable by selecting the Upgrade npm Packages button with version 1.15.3 of the "GitHub Copilot modernization" extension.

I am attaching the before and after content in some markdown files to this issue.

I ask you to please research why the upgrade caused this app to stop working.

The other choices are in this repo also. I will now switch to my second choice wesleyfuchter-todolist-spring-react in the hopes the upgrade will "just work".

05-mehmet-app-bug-report.md
05-perform-frontend-upgrade.md

Expected behavior

I exect the app will still run after Upgrade npm packages.

Screenshots & Logs

No response