I don't normally like to dig up posts from the grave but I had exactly the same problem and your fix helped me out. I've added a note on the Grunt page in the dev docs.
I can't help feeling that the cost of entry to Javascript dev in Moodle is creeping higher. There's no more avoiding a reasonably good understanding of node and friends.
I can't help feeling that the cost of entry to Javascript dev in Moodle is creeping higher. There's no more avoiding a reasonably good understanding of node and friends.