What can I do to make the build work properly?

Question

I have this structure:
https://i.sstatic.net/oj2KH.png\ And this webpack configs:
base:

const path = require('path');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const CopyWebpackPlugin = require('copy-webpack-plugin');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const { VueLoaderPlugin } = require('vue-loader');
 
const PATHS = {
    src: path.join(__dirname, '../src'),
    dist: path.join(__dirname, '../dist'),
    assets: 'assets/'
}
 
const PostcssLoaderConfig = {
    loader: 'postcss-loader',
    options: { sourceMap: true, postcssOptions: { config: `${PATHS.src}/assets/js/configs/postcss.config.js` } }
}
 
module.exports = {
    externals: {
        paths: PATHS,
        plugins: {
            miniCssExtract: MiniCssExtractPlugin
        },
        configs: {
            postCssLoader: PostcssLoaderConfig,
        }
    },
    entry: {
        app: PATHS.src
    },
    output: {
        path: PATHS.dist,
        filename: `${PATHS.assets}js/[name].js`,
        publicPath: '/'
    },
    optimization: {
        splitChunks: {
            cacheGroups: {
                vendor: {
                    name: 'vendors',
                    test: /node_modules/,
                    chunks: 'all',
                    enforce: true
                }
            }
        }
    },
    plugins: [
        new VueLoaderPlugin(),
        new MiniCssExtractPlugin({
            filename: `${PATHS.assets}css/[name].css`
        }),
        new HtmlWebpackPlugin({
            hash: false,
            template: `${PATHS.src}/index.html`,
            filename: './index.html'
        }),
        new CopyWebpackPlugin({
            patterns: [
                { from: `${PATHS.src}/assets/img/`, to: `${PATHS.assets}img` },
                { from: `${PATHS.src}/assets/fonts/`, to: `${PATHS.assets}fonts` },
                { from: `${PATHS.src}/static/`, to: `` }
            ]
        })
    ],
    module: {
        rules: [
            {
                test: /\.js$/,
                use: { loader: 'babel-loader', options: { presets: ['@babel/preset-env'] } }
            },
            {
                test: /\.((c|sa|sc)ss)$/i,
                use: [MiniCssExtractPlugin.loader, { loader: 'css-loader', options: { sourceMap: true } },
                    PostcssLoaderConfig, { loader: 'sass-loader', options: { sourceMap: true } } ]
            },
            {
                test: /\.vue$/,
                loader: 'vue-loader',
                options: {
                    loader: {
                        scss: 'vue-style-loader!css-loader!sass-loader'
                    }
                } 
            },
            {
                test: /\.(png|jpg|gif|svg)$/,
                loader: 'file-loader',
                options: {
                    name: '[name].[ext]'
                }
            },
            {
                test: /\.(woff(2)?|ttf|eot|svg)(\?v=\d+\.\d+\.\d+)?$/,
                loader: 'file-loader',
                options: {
                    name: '[name].[ext]'
                }
            },
        ]
    },
    resolve: {
        alias: {
            'vue$': 'vue/dist/vue.js'
        }
    }
};

dev:

const webpack = require('webpack');
const webpackServer = require('webpack-dev-server');
const { merge } = require('webpack-merge');
const baseWebpackConfig = require('./webpack.base.conf');

const devWebpackConfig = merge(baseWebpackConfig, {
    mode: 'development',
    devtool: 'eval-cheap-module-source-map',
    devServer: {
        contentBase: baseWebpackConfig.externals.paths.dist,
        port: 8081,
        overlay: true
    },
    plugins: [
        new webpack.SourceMapDevToolPlugin({
            filename: '[file].map'
        })
    ]
})

module.exports = new Promise((resolve, reject) => {
    resolve(devWebpackConfig)
})

build:

const webpack = require('webpack');
const { merge } = require('webpack-merge');
const baseWebpackConfig = require('./webpack.base.conf');

const buildWebpackConfig = merge(baseWebpackConfig, {
    mode: 'production',
    plugins: []
})

module.exports = new Promise((resolve, reject) => {
    resolve(buildWebpackConfig)
})

I have no issues with dev config, it works fine, but build version looks like:
https://i.sstatic.net/lxYbr.png
HTML:
https://i.sstatic.net/IkFXd.png
Console:
https://i.sstatic.net/sICyX.png
Also, I noticed that some files used in SCSS are in the dist root, although they are not needed there (since the assets folder copied)
What can I do to make the build work properly?

Answer 1

Config was created for Webpack 4, but Webpack 5 was installed.