build(webpack): clean dist dir before builds

Clean the dist dir before builds to remove stale/unwanted build results

package.json

@@ -168,6 +168,7 @@
     "babel-register": "^6.26.0",
     "browserslist": "^4.0.0",
     "chalk": "^2.4.1",
+    "clean-webpack-plugin": "^0.1.19",
     "concurrently": "^3.6.0",
     "connect-history-api-fallback": "^1.5.0",
     "cross-env": "^5.2.0",

webpack.config.renderer.prod.js

@@ -7,6 +7,7 @@ import ExtractTextPlugin from 'extract-text-webpack-plugin'
 import HtmlWebpackPlugin from 'html-webpack-plugin'
 import CspHtmlWebpackPlugin from 'csp-html-webpack-plugin'
 import { BundleAnalyzerPlugin } from 'webpack-bundle-analyzer'
+import CleanWebpackPlugin from 'clean-webpack-plugin'
 import merge from 'webpack-merge'
 import baseConfig from './webpack.config.base'
 
@@ -141,6 +142,8 @@ export default merge.smart(baseConfig, {
   },
 
   plugins: [
+    new CleanWebpackPlugin(['app/dist']),
+
     new ExtractTextPlugin('style.css'),
 
     new BundleAnalyzerPlugin({

yarn.lock

@@ -2722,6 +2722,12 @@ clean-css@4.1.x:
   dependencies:
     source-map "0.5.x"
 
+clean-webpack-plugin@^0.1.19:
+  version "0.1.19"
+  resolved "https://registry.yarnpkg.com/clean-webpack-plugin/-/clean-webpack-plugin-0.1.19.tgz#ceda8bb96b00fe168e9b080272960d20fdcadd6d"
+  dependencies:
+    rimraf "^2.6.1"
+
 cli-boxes@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/cli-boxes/-/cli-boxes-1.0.0.tgz#4fa917c3e59c94a004cd61f8ee509da651687143"