additional webpack4 migration steps: add mode to webpack config; add webpack-cli to package.json

client/configuration/webpack/webpack.config.dev.js

@@ -8,6 +8,7 @@ const src = path.resolve("src");
 const nodeModules = path.resolve("node_modules");
 
 module.exports = {
+  mode: "development",
   devtool: "eval",
   entry: [
     "webpack-hot-middleware/client?quiet=true&noInfo=true",

client/configuration/webpack/webpack.config.prod.js

@@ -15,6 +15,7 @@ const nodeModules = path.resolve("node_modules");
 const publicPath = "/";
 
 module.exports = {
+  mode: "production",
   bail: true,
   devtool: "cheap-source-map",
   entry: [require.resolve("../polyfills/polyfills"), path.join(src, "index")],

client/package.json

@@ -111,6 +111,7 @@
     "url-loader": "^0.6.0",
     "web-app-manifest-loader": "^0.1.1",
     "webpack": "^4.16.0",
+    "webpack-cli": "^3.1.0",
     "webpack-dev-middleware": "^1.6.1",
     "webpack-hot-middleware": "^2.22.3"
   },