Sometimes it’s because Chrome is in the middle of an update. Even if it doesn’t prompt for restart, go to chrome://help/ and manually restart from there. Simply quitting Chrome and restarting the app might not work.
OS X provides a pretty handy way of combining PDFs in Preview. Go Menu -> View -> Contact Sheet with both files, and drag additional PDF pages onto the first one. However, sometimes it just doesn’t seem to work.
You’d get the Unknown Provider error if you’re publishing compressed CoffeeScript. It usually goes like this:
Error: [$injector:unpr] Unknown provider...