TypeError: Object [object Object], [object Object] has no method find

I have following a tutorial in a book called "Sitepoint Full Stack Javascript with MEAN" and I've just finished chapter 6, and should've created a "server" with a "database". The database is nothing more than a JSON document. However, even though (what I can see), my code is a direct copy of his, I get the error mentioned in the title when i try to run it. It's var result = data.find(function(item) {... (line located in employees.js, about line 16) that is the cause of this problem. I can't see what else I can do, and hope you people can find a solution to my problem.

I have a couple of different files which I use for this.

Index.js:

var http = require('http');
var employeeService = require('./lib/employees');
var responder = require('./lib/responseGenerator');
var staticFile = responder.staticFile('/public');

http.createServer(function(req,res) {
    // a parsed url to work with in case there are parameters
    var _url;

    //In case the client uses lower case for methods
    req.method = req.method.toUpperCase();
    console.log(req.method + ' ' + req.url);

    if (req.method !== 'GET') {
        res.writeHead(501, {
            'Content-Type': 'text/plain'
        });
        return res.end(req.method + ' is not implemented by this server.');
    }

    if (_url = /^\/employees$/i.exec(req.url)) {
        //return a list of employess
        employeeService.getEmployees(function(error, data){
            if(error) {
                return responder.send500(error, res);
            }
            return responder.sendJson(data,res);
        });
    } else if (_url = /^\/employees\/(\d+)$/i.exec(req.url)){ 
        //find the employee by the id in the route
        employeeService.getEmployee(_url[1], function(error, data) {
            if (error) {
                return responder.send500(error, res);
            }
            if(!data) {
                return responder.send404(res);
            }
            return responder.sendJson(data,res);
        });

    } else{
            res.writeHead(200);
            res.end("static file")
    }


}).listen(1337);

console.log('server running');

employee.js

var employeeDb = require('../database/employees.json')

exports.getEmployees = getEmployees;
exports.getEmployee = getEmployee;

function getEmployees (callback) {
    setTimeout(function() {
        callback(null, employeeDb);
    }, 500);
}

function getEmployee (employeeId, callback) {
    getEmployees(function (error, data) {
        if (error) {
            return callback(error);
        }
        var result = data.find(function(item) {
            return item.id === employeeId;
        });
        callback(null, result)
    });
}

responseGenerator.js

var fs = require('fs');

exports.send404 = function (reponse) {
    console.error('Resource not found');
    response.writeHead(404, {
        'Content-Type': 'text/plain'
    });
    response.end('Not Found');
}

exports.sendJson = function(data, response) {
    response.writeHead(200, {
        'Content-Type': 'application/json'
    });

    response.end(JSON.stringify(data));
}

exports.send500 = function(data, response) {
    console.error(data.red);
    reponse.writeHead(500, {
        'Content-Type': 'text/plain'
    });
    response.end(data);
}

exports.staticFile = function(staticPath) {
    return function(data, response) {
        var readStream;

        // Fix so routes to /home and /home.html both work
        data = data.replace(/^(\/home)(.html)?$/i,'$1.html');
        data = '.' + staticPath + data;

        fs.stat(data, function(error, stats) {
            if (error || stats.isDirectory()) {
                return exports.send404(response);
            }

            readstream = fs.createReadStream(data);
            return readStream.pipe(response);
        });
    }
}

employees.json("database")

[
    {
        "id": "103",
        "name": {
            "first": "Colin",
            "last": "Ihrig"
        },
        "address": {
            "lines": ["11 Wall Street"],
            "city": "New York",
            "state": "NY",
            "zip": 10118
        }
    },
    {
        "id": "104",
        "name": {
            "first": "Idiot",
            "last": "Fjols"
        },
        "address": {
            "lines": ["Total taber"],
            "city": "Feeeee",
            "state": "Whatever",
            "zip": 10112
        }
    }


]

Hope you can help.