webpack: don't precache .DS_Store in sw.js (#64)

webpack.config.js

@@ -48,6 +48,11 @@ module.exports = [{
     }),
     ...(process.env.NODE_ENV === 'production' ? [
       new WorkboxPlugin.GenerateSW({
+          exclude: [
+            /\.map$/,
+            /^manifest.*\.js$/,
+            /.*?\.DS_Store$/,
+          ],
           // these options encourage the ServiceWorkers to get in there fast     
           // and not allow any straggling "old" SWs to hang around     
           swDest: path.join(__dirname, "dist", 'sw.js'),