Fix react-scripts build error

./src/components/PageWrapper.js
TypeError: Cannot read property 'forEach' of undefined

was being thrown during build. According to a github issue downgrading is the solution

facebook/create-react-app#7753

package.json

@@ -40,7 +40,7 @@
     "react-dom": "^16.5.2",
     "react-helmet": "^5.2.0",
     "react-router-dom": "^4.3.1",
-    "react-scripts": "^3.0.1"
+    "react-scripts": "3.0.1"
   },
   "devDependencies": {
     "autoprefixer": "^9.6.1",