"TypeError: Parameter "url" must be a string, not undefined" when running heroku app locally

I followed this tutorial here, instead of only hosting the code on herokus git I hosted it on git. It works on heroku the app itself but when I pull it and run it locally using node server.js and It gives me the error below.

1. I've updated node

2. Run it using heroku local and heroku local web, same thing...

3. Making the app again from fresh.

I suspect its something to do with the mlab connection not getting through. Anyways any help greatly appreciated.

C:\College\WebProg4\foodonline>node server.js
url.js:88
    throw new TypeError('Parameter "url" must be a string, not ' + typeof url);
    ^

TypeError: Parameter "url" must be a string, not undefined
    at Url.parse (url.js:88:11)
    at Object.urlParse [as parse] (url.js:82:5)
    at module.exports (C:\College\WebProg4\foodonline\node_modules\mongodb\lib\url_parser.js:15:23)
    at connect (C:\College\WebProg4\foodonline\node_modules\mongodb\lib\mongo_client.js:403:16)
    at Function.MongoClient.connect (C:\College\WebProg4\foodonline\node_modules\mongodb\lib\mongo_client.js:227:3)
    at Object.<anonymous> (C:\College\WebProg4\foodonline\server.js:19:21)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)

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