Testing local site on a Mac

[DanCollinz]

I am tying to run sitespeedioto test a local site on my Mac. It opens the browser, which says page can't be found. If I go headless, I get an error, Fatal error: Cannot read property 'har' of undefined.

Seems like this should work, as a grunt task, I want to test my local site before changes are merged into master and deployed.