tweak webpack config to make it faster and more correct

webpack.client.config.js

@@ -9,7 +9,7 @@ module.exports = {
   entry: config.client.entry(),
   output: config.client.output(),
   resolve: {
-    extensions: ['.js', '.html']
+    extensions: ['.js', '.json', '.html']
   },
   mode: isDev ? 'development' : 'production',
   module: {
@@ -36,11 +36,6 @@ module.exports = {
       },
       !isDev && {
         test: /\.css$/,
-        /* disable while https://github.com/sveltejs/sapper/issues/79 is open */
-        /* use: ExtractTextPlugin.extract({
-          fallback: 'style-loader',
-          use: [{ loader: 'css-loader', options: { sourceMap:isDev } }]
-        }) */
         use: [
           { loader: 'style-loader' },
           { loader: 'css-loader' }
@@ -51,19 +46,18 @@ module.exports = {
   node: {
     setImmediate: false
   },
-  plugins: isDev ? [
+  plugins: [
+    new LodashModuleReplacementPlugin({
+      collections: true,
+      caching: true
+    })
+  ].concat(isDev ? [
     new webpack.HotModuleReplacementPlugin()
   ] : [
     new webpack.DefinePlugin({
       'process.browser': true,
       'process.env.NODE_ENV': '"production"'
     }),
-    /* disable while https://github.com/sveltejs/sapper/issues/79 is open */
-    // new ExtractTextPlugin('main.css'),
-    new LodashModuleReplacementPlugin({
-      collections: true,
-      caching: true
-    }),
     new BundleAnalyzerPlugin({ // generates report.html and stats.json
       analyzerMode: 'static',
       generateStatsFile: true,
@@ -74,6 +68,6 @@ module.exports = {
       openAnalyzer: false,
       logLevel: 'silent' // do not bother Webpacker, who runs with --json and parses stdout
     })
-  ],
+  ]),
-  devtool: isDev ? 'cheap-module-source-map' : 'source-map'
+  devtool: isDev ? 'cheap-module-eval-source-map' : 'source-map'
 }