chore: fix eslint warning in example (#1922)

Author: Alan Wang

examples/shopping-cart/api/shop.js

@@ -2,9 +2,9 @@
  * Mocking client-server processing
  */
 const _products = [
-  {"id": 1, "title": "iPad 4 Mini", "price": 500.01, "inventory": 2},
-  {"id": 2, "title": "H&M T-Shirt White", "price": 10.99, "inventory": 10},
-  {"id": 3, "title": "Charli XCX - Sucker CD", "price": 19.99, "inventory": 5}
+  { 'id': 1, 'title': 'iPad 4 Mini', 'price': 500.01, 'inventory': 2 },
+  { 'id': 2, 'title': 'H&M T-Shirt White', 'price': 10.99, 'inventory': 10 },
+  { 'id': 3, 'title': 'Charli XCX - Sucker CD', 'price': 19.99, 'inventory': 5 }
 ]
 
 export default {

examples/webpack.config.js

@@ -56,7 +56,7 @@ module.exports = {
     new webpack.DefinePlugin({
       __DEV__: JSON.stringify(true),
       'process.env': {
-        NODE_ENV: JSON.stringify(process.env.NODE_ENV),
+        NODE_ENV: JSON.stringify(process.env.NODE_ENV)
       }
     })
   ]