This usually means that the ruby devkit is not installed, though I am not a mac user so not sure how that applies to the mac os.
check this post - and the guide @MichaelCurrin links to:
This usually means that the ruby devkit is not installed, though I am not a mac user so not sure how that applies to the mac os.
check this post - and the guide @MichaelCurrin links to: