How to implement SASS into react with raw webpack?

So I was trying to use Bulma and got a can't import _varibales.sass, which I have in my src folder. So I thought it was because I didn't configure webpack to support Sass.

So I followed the configuration instructions from this tutorial, but then I got a loader error. This is my first time using raw webpack as opposed to CRA. I did this because I wanted to understand Webpack and Babel more.

Another thing I have tried is the Webpack configuration found on the dart-sass configuration.

My error right now is:

[webpack-cli] Invalid configuration object. Webpack has been initialized using a configuration object that does not match the API schema.

configuration.module.rules[2] should be one of these: ["..." | object { compiler?, dependency?, descriptionData?, enforce?, exclude?, generator?, include?, issuer?, issuerLayer?, layer?, loader?, mimetype?, oneOf?, options?, parser?, realResource?, resolve?, resource?, resourceFragment?, resourceQuery?, rules?, sideEffects?, test?, type?, use? }, ...]

-> A rule. Details: * configuration.module.rules[2].loader should be a non-empty string.

And my webpack.config.js looks like this:

const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const Dotenv = require('dotenv-webpack');
const MiniCssExtractPlugin = require('mini-css-extract-plugin')
const isDevelopment = process.env.NODE_ENV === 'development'

module.exports = {
  mode: 'development',
  entry: path.resolve(__dirname, 'src', 'index.js'),
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: 'bundle.js',
    publicPath: '/'
  },
  module: {
    rules: [
      {
        test: /\.jsx?$/,
        exclude: /node_modules/,
        loader: 'babel-loader',
        options: {
          presets: ["@babel/preset-env", "@babel/preset-react"]
        }
      },
      {
        test: /\.module\.s(a|c)ss$/,
        loader: [
          isDevelopment ? 'style-loader' : MiniCssExtractPlugin.loader,
          {
            loader: 'css-loader',
            options: {
              modules: true,
              sourceMap: isDevelopment
            }
          },
          {
            loader: 'sass-loader',
            options: {
              sourceMap: isDevelopment
            }
          }
        ]
      },
      {
        test: /\.s(a|c)ss$/,
        exclude: /\.module.(s(a|c)ss)$/,
        loader: [
          isDevelopment ? 'style-loader' : MiniCssExtractPlugin.loader,
          'css-loader',
          {
            loader: 'sass-loader',
            options: {
              sourceMap: isDevelopment
            }
          }
        ]
      }
    ]
  },
  devServer: {
    historyApiFallback: true,
  },
  plugins: [
    new HtmlWebpackPlugin({ template: path.resolve(__dirname, 'src', 'index.html') }),
    new Dotenv(),
    new MiniCssExtractPlugin({
      filename: isDevelopment ? '[name.css]' : '[name].[hash].css',
      chunkFilename: isDevelopment ? '[id].css' : '[id].[hash].css'
    })
  ],
  resolve: {
    extensions: [".js", ".jsx", ".sass", ".scss"]
  }
};

You use WebPack version 5+. Downgrade to a lower version of WebPack to assure compatibility.

"webpack": "^4.41.5"

In case you need to stick with the 5+ version or to learn more about the error in the webpack.config.json configuration file, refer to Webpack v4 to v5 migration.