'arguments to path.join must be strings' typeerror during ember serve and ember build

I just started working on some ember tutorials and I wanted to try and make a gh-pages branch so I could host the project. I was looking at tutorials on how to do so and made some changes to my config/environment.js. I was following the steps from ember-cli-github-pages but ran into some issues, so I deleted the branch and started to try again, however now I am getting the following error when I try to build or even run the server.

TypeError: Arguments to path.join must be strings
at Object.posix.join (path.js:488:13)
at AddonDiscovery.<anonymous> (/usr/local/lib/node_modules/ember-cli/lib/models/addon-discovery.js:107:24)
at Array.map (native)
at AddonDiscovery.discoverFromDependencies (/usr/local/lib/node_modules/ember-cli/lib/models/addon-discovery.js:97:68)
at AddonDiscovery.discoverProjectAddons (/usr/local/lib/node_modules/ember-cli/lib/models/addon-discovery.js:45:31)
at Project.discoverAddons (/usr/local/lib/node_modules/ember-cli/lib/models/project.js:317:40)
at Project.initializeAddons (/usr/local/lib/node_modules/ember-cli/lib/models/project.js:336:8)
at Project.eachAddonCommand (/usr/local/lib/node_modules/ember-cli/lib/models/project.js:389:10)
at module.exports (/usr/local/lib/node_modules/ember-cli/lib/cli/lookup-command.js:34:13)
at CLI.<anonymous> (/usr/local/lib/node_modules/ember-cli/lib/cli/cli.js:35:26)

Still being quite new, I've searched throughout stackoverflow and Google to find a hint of what is going wrong and how to fix it but nothing so far. Here is what my environment.js file looks like

module.exports = function(environment) {
var ENV = {
modulePrefix: '',
environment: environment,
baseURL: '/',
locationType: 'auto',
EmberENV: {
  FEATURES: {
    // Here you can enable experimental features on an ember canary build
    // e.g. 'with-controller': true
  }
},

APP: {
  // Here you can pass flags/options to your application instance
  // when it is created
}
};

if (environment === 'development') {
// ENV.APP.LOG_RESOLVER = true;
// ENV.APP.LOG_ACTIVE_GENERATION = true;
// ENV.APP.LOG_TRANSITIONS = true;
// ENV.APP.LOG_TRANSITIONS_INTERNAL = true;
// ENV.APP.LOG_VIEW_LOOKUPS = true;
}

if (environment === 'test') {
// Testem prefers this...
ENV.baseURL = '/';
ENV.locationType = 'none';

// keep test console output quieter
ENV.APP.LOG_ACTIVE_GENERATION = false;
ENV.APP.LOG_VIEW_LOOKUPS = false;

ENV.APP.rootElement = '#ember-testing';
}

if (environment === 'production') {

}

return ENV;
}; 

Any hint or push in the right direction would be greatly appreciated or where I should look on how to get rid of this error.

I'm using mac os x

:> ember --version
version: 1.13.1
node: 0.12.7
npm: 2.12.1

Thanks.