'TypeError: Cannot read property 'Swimming is great for the joints' of undefined'

Hey everyone,

I was first running into an issue where I was unable to view the any objects in the console on the Node Inspector page. I understand the idea though so I kept going, but now I'm running into a problem in which I can't retrieve individual posts. The error I get is as follows:

TypeError: Cannot read property 'Swimming is great for the joints' of undefined at /Users/donhamiltoniii/Desktop/projects/express-basics/src/app.js:16:18 at Layer.handle as handle_request at next (/Users/donhamiltoniii/Desktop/projects/express-basics/node_modules/express/lib/router/route.js:131:13) at Route.dispatch (/Users/donhamiltoniii/Desktop/projects/express-basics/node_modules/express/lib/router/route.js:112:3) at Layer.handle as handle_request at /Users/donhamiltoniii/Desktop/projects/express-basics/node_modules/express/lib/router/index.js:277:22 at param (/Users/donhamiltoniii/Desktop/projects/express-basics/node_modules/express/lib/router/index.js:349:14) at param (/Users/donhamiltoniii/Desktop/projects/express-basics/node_modules/express/lib/router/index.js:365:14) at Function.process_params (/Users/donhamiltoniii/Desktop/projects/express-basics/node_modules/express/lib/router/index.js:410:3) at next (/Users/donhamiltoniii/Desktop/projects/express-basics/node_modules/express/lib/router/index.js:271:10)

my code is below:

'use strict';

var express = require('express'),
      posts = require('./mock/posts.json');

var app = express();

app.get('/', function(req, res) {
    res.send("<h1>I am loving Treehouse!</h1>");
});

app.get('/blog/:title?', function(req, res) {
    var title = req.params.title;
    if (title === undefined) {
        res.send("this page is under construction")
    } else {
        var post = post[title];
        res.send(post);
    }
});

app.listen(3000, function(){
    console.log("The frontend server is running on port 3000!")
});

Thanks in advance for any help