ReferenceError: loader is not defined - node.js

Question

I have been developing a React app with nodejs backend. Now I'm getting this error when I run npm run build. I have update node and npm to latest versions. I'm getting the following error log in the console.
$ npm run build
> client#0.1.0 build C:\Demos\mern-course\client
> react-scripts build
Creating an optimized production build...
Failed to compile.
./src/App.css
ReferenceError: loader is not defined
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! client#0.1.0 build: `react-scripts build`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the client#0.1.0 build script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
My package.json is as follows.
{
"name": "client",
"version": "0.1.0",
"private": true,
"dependencies": {
"#testing-library/jest-dom": "^4.2.4",
"#testing-library/react": "^9.4.0",
"#testing-library/user-event": "^7.2.1",
"axios": "^0.19.2",
"bootstrap": "^4.4.1",
"react": "^16.12.0",
"react-dom": "^16.12.0",
"react-redux": "^7.2.0",
"react-scripts": "^3.4.0",
"react-transition-group": "^4.3.0",
"reactstrap": "^8.4.1",
"redux": "^4.0.5",
"redux-thunk": "^2.3.0",
"uuid": "^3.4.0"
},
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"test": "react-scripts test",
"eject": "react-scripts eject"
},
"proxy": "http://localhost:5000",
"eslintConfig": {
"extends": "react-app"
},
"browserslist": {
"production": [
">0.2%",
"not dead",
"not op_mini all"
],
"development": [
"last 1 chrome version",
"last 1 firefox version",
"last 1 safari version"
]
}
}
Here is the link for github repo for the code.

Answer 1

./src/App.css
ReferenceError: loader is not defined
You need to check that you are importing App.css correctly. This should be in your App.js

Answer 2

Replace "css-loader" folder in front end node-modules folder with another "css-loader" which has taken from working react project.