title: `json.decoder.JSONDecodeError` while making an app using Python and Flask
body: <p>I am <strong>trying to get a book's review data by using Goodread's api</strong> while building an app with Flask. This is part of a project that I am doing from a tutorial series called CS50 Web Programming Series. </p>
  
  <p>So I have been trying to pull the data by using Python's <code>Request</code> module and stored that data in a variable and later Jsonify it. So that when a user types in <code>/api/&lt;a book's isbn number&gt;</code> then it should return a Jsonified data of a book.</p>
  
  <pre class="lang-py prettyprint-override"><code>@app.route('/api/&lt;isbn&gt;', methods = ['GET'])
  def isbn(isbn):
      #import api from Goodreads (stats) 
      r = requests.get("https://www.goodreads.com/book/review_counts.json", params={"key": "L3FHyOR3IhCo3kctcUz3zg", "isbns": "isbn"}).json()
      res = db.execute("SELECT * FROM books WHERE isbn = :isbn", {"isbn": isbn}).fetchone()
      print ('res')
      if res is None: 
          return "404 error"
      return jsonify({
          "title": res.title,
          "author": res.author,
          "year": res.year,
          "isbn": res.isbn,
          "review_count": r.reviews_count,
          "average_score": r.average_rating
      })
  </code></pre>
  
  <p>The error that I am getting when I type in an isbn looks like this. <a href="http://prntscr.com/ojnwbw" rel="nofollow noreferrer">http://prntscr.com/ojnwbw</a> </p>
  
  <p>It seems so that I am making a major issue on the line where I define <code>r</code>. Could anyone help troubleshoot this problem?</p>