Show proper message if api request is forbidden (403 status)

[devfake]

It could be the case, that the API volume of Google Books is exhausted. The response will return a 403 status code.

I updated the backend and return this status to the client (0d65914).

What we need now is to display a message in the frontend. The best thing we can do is create a new variable, and set it to true if the response is a 403. And show a proper message in the template, similiar to the Nothing found :( span.

To test this, you can replace the line 24 in express.js instead of res.json(formattedData) with res.json(forbiddenResponse()).

Bonus point: Move the hardcodet status codes (404 for example) to own constants on top of the script (:

[ccmetz]

Hey I would love to work on this issue! Could you assign me to it?