Moodle Gruntfile.js will not work on Windows because it does not have the PWD environment variable.

I've been trying to figure out how to create a Javascript Module and add it to a theme, so I copied the example from the Moodle document Javascript Modules. I used componant 'theme' not 'block' as the example gave. So where the example used 'block_overview/helloworld' I used 'theme_graphite/helloworld'.
I added the call in my layout file for the frontpage...
After running 'grunt' I got the following error.

C:\wamp\www\moodle29\theme\graphite\amd>grunt

Loading "Gruntfile.js" tasks...ERROR

>> TypeError: Arguments to path.resolve must be strings

Warning: Task "default" not found. Use --force to continue.

Aborted due to warnings.

Here is a link to a comment gb2048 made about the problem:
https://moodle.org/mod/forum/discuss.php?d=312492#p1251016