🐛 Add sourcemap generation for minified version

Author: apertureless

build/webpack.release.min.js

@@ -3,12 +3,10 @@ var webpack = require('webpack')
 
 config.output.filename = config.output.filename.replace(/\.js$/, '.min.js')
 
-delete config.devtool
-
 config.plugins = [
   new webpack.optimize.ModuleConcatenationPlugin(),
   new webpack.optimize.UglifyJsPlugin({
-    sourceMap: false,
+    sourceMap: true,
     compress: {
       warnings: false
     }