FIXING THE CORE-JS ERROR

The core-js error is usually caused by an update or change in the current core-js version. A quick fix is usually to change the core-js version in package.json to the latest which is @3.15.2 or whichever is right now.
quick fixes you can do

1. copy the code in this github repo and paste in the file directory in node modules.

If the error still persists

1. run npm clear cache. Add --force add the end if necessary.
2. Close all IDE instances if any error still persists.
3. run npm i core-js@3.15.2

Hope this helps.