Also any information about your environment too might be helpful.
Similar grunt or npm issues can be found, one in particular is here
Theme installation requires multiple steps that can be seen here
I personally have to run npm install and bower install separately for some reason I haven’t cared enough to track down yet too, so make sure all packages got installed.
Also, did you alter your grunt file at all? That error seems to imply that it was attempting to read something that doesn’t exist. Can you run any of the grunt subroutines? Say grunt:jshint?