How to use the sapper/config/webpack.js.server function in sapper

},
		mode,
		plugins: [
			// pending https://github.com/sveltejs/svelte/issues/2377
			// dev && new webpack.HotModuleReplacementPlugin(),
			new webpack.DefinePlugin({
				'process.browser': true,
				'process.env.NODE_ENV': JSON.stringify(mode)
			}),
		].filter(Boolean),
		devtool: dev && 'inline-source-map'
	},

	server: {
		entry: config.server.entry(),
		output: config.server.output(),
		target: 'node',
		resolve: { alias, extensions, mainFields },
		externals: Object.keys(pkg.dependencies).concat('encoding'),
		module: {
			rules: [
				{
					test: /\.(svelte|html)$/,
					use: {
						loader: 'svelte-loader',
						options: {
							css: false,
							generate: 'ssr',
							dev
						}
					}
				}

},
    mode,
    plugins: [
      new MiniCssExtractPlugin({ filename: dev ? "[name].css" : "[name]-[contenthash].css" }),
      // pending https://github.com/sveltejs/svelte/issues/2377
      // dev && new webpack.HotModuleReplacementPlugin(),
      new webpack.DefinePlugin({
        "process.browser": true,
        "process.env.NODE_ENV": JSON.stringify(mode)
      })
    ].filter(Boolean),
    devtool: dev && "inline-source-map"
  },

  server: {
    entry: config.server.entry(),
    output: config.server.output(),
    target: "node",
    resolve: { extensions, mainFields },
    externals: Object.keys(pkg.dependencies).concat("encoding"),
    module: {
      rules: [
        cssConfig,
        {
          test: /\.(svelte|html)$/,
          use: {
            loader: "svelte-loader",
            options: {
              css: false,
              generate: "ssr",
              dev
            }

],
    },
    mode,
    plugins: [
      // Pending https://github.com/sveltejs/svelte/issues/2377.
      // dev && new webpack.HotModuleReplacementPlugin(),
      new webpack.DefinePlugin({
        'process.browser': true,
        'process.env.NODE_ENV': JSON.stringify(mode),
      }),
    ].filter(Boolean),
    devtool: dev && 'inline-source-map',
  },

  server: {
    entry: config.server.entry(),
    output: config.server.output(),
    target: 'node',
    resolve: { extensions, mainFields },
    externals: Object.keys(pkg.dependencies).concat('encoding'),
    module: {
      rules: [
        {
          test: /\.(svelte|html)$/,
          use: {
            loader: 'svelte-loader',
            options: {
              preprocess,
              css: false,
              generate: 'ssr',
              dev,
            },

},
    mode,
    plugins: [
      // Pending https://github.com/sveltejs/svelte/issues/2377.
      // dev && new webpack.HotModuleReplacementPlugin(),
      new webpack.DefinePlugin({
        'process.browser': true,
        'process.env.NODE_ENV': JSON.stringify(mode),
      }),
    ].filter(Boolean),
    devtool: dev && 'inline-source-map',
  },

  server: {
    entry: config.server.entry(),
    output: config.server.output(),
    target: 'node',
    resolve: { extensions, mainFields },
    externals: Object.keys(pkg.dependencies).concat('encoding'),
    module: {
      rules: [
        {
          test: /\.(svelte|html)$/,
          use: {
            loader: 'svelte-loader',
            options: {
              preprocess,
              css: false,
              generate: 'ssr',
              dev,
            },
          },

filename: '[name].css'
			}),
			// new CleanWebpackPlugin(['public'], {
			// 	exclude: [],
			// 	verbose: true
			// }),
		].filter(Boolean),
		devtool: dev && 'inline-source-map',
		stats: {
			warnings: false
		}
	},

	server: {
		entry: config.server.entry(),
		output: config.server.output(),
		target: 'node',
		resolve: { alias, extensions, mainFields },
		externals: Object.keys(pkg.dependencies).concat('encoding'),
		module: {
			rules: [
				{
					test: /\.(svelte|html)$/,
					use: {
						loader: 'svelte-loader',
						options: {
							css: false,
							generate: 'ssr',
							dev,
							preprocess
						}
					}

mode,
    plugins: [
      new MiniCssExtractPlugin({ filename: dev ? "[name].css" : "[name]-[contenthash].css" }),
      // pending https://github.com/sveltejs/svelte/issues/2377
      // dev && new webpack.HotModuleReplacementPlugin(),
      new webpack.DefinePlugin({
        "process.browser": true,
        "process.env.NODE_ENV": JSON.stringify(mode)
      })
    ].filter(Boolean),
    devtool: dev && "inline-source-map"
  },

  server: {
    entry: config.server.entry(),
    output: config.server.output(),
    target: "node",
    resolve: { extensions, mainFields },
    externals: Object.keys(pkg.dependencies).concat("encoding"),
    module: {
      rules: [
        cssConfig,
        {
          test: /\.(svelte|html)$/,
          use: {
            loader: "svelte-loader",
            options: {
              css: false,
              generate: "ssr",
              dev
            }
          }

]
		},
		mode,
		plugins: [
			// pending https://github.com/sveltejs/svelte/issues/2377
			// dev && new webpack.HotModuleReplacementPlugin(),
			new webpack.DefinePlugin({
				'process.browser': true,
				'process.env.NODE_ENV': JSON.stringify(mode)
			}),
		].filter(Boolean),
		devtool: dev && 'inline-source-map'
	},

	server: {
		entry: config.server.entry(),
		output: config.server.output(),
		target: 'node',
		resolve: { alias, extensions, mainFields },
		externals: Object.keys(pkg.dependencies).concat('encoding'),
		module: {
			rules: [
				{
					test: /\.(svelte|html)$/,
					use: {
						loader: 'svelte-loader',
						options: {
							css: false,
							generate: 'ssr',
							dev
						}
					}

new MiniCssExtractPlugin({
				filename: '[name].css'
			}),
			// new CleanWebpackPlugin(['public'], {
			// 	exclude: [],
			// 	verbose: true
			// }),
		].filter(Boolean),
		devtool: dev && 'inline-source-map',
		stats: {
			warnings: false
		}
	},

	server: {
		entry: config.server.entry(),
		output: config.server.output(),
		target: 'node',
		resolve: { alias, extensions, mainFields },
		externals: Object.keys(pkg.dependencies).concat('encoding'),
		module: {
			rules: [
				{
					test: /\.(svelte|html)$/,
					use: {
						loader: 'svelte-loader',
						options: {
							css: false,
							generate: 'ssr',
							dev,
							preprocess
						}