Vue.js Nightwatch Error connecting to localhost on port 4444

 I was receiving the above error when attempting to run my my first tests. 

Also note this in the error message. 

""Expected browser binary location, but unable to find binary in default location, no 'moz:firefoxOptions.binary' capability provided, and no binary flag set on the command line""

The reason for this was that I needed to install Firefox ( I'd recently renewed my laptop and it hadn't added this browser yet ! )