Unhandled error when computername not set on Mac OS

[Holocene]

Hi,

It seems that when the ComputerName is not set in Mac OS, the library fails in an unexpected way because scutil does not return a result. Please see this stackoverflow question:

http://stackoverflow.com/questions/36155236/nodejs-error-typeerror-cannot-read-property-stdout-of-undefined

Perhaps the code should throw if a err has a value?