grunt - getting "Local Npm module "xxx" not found. Is it installed?" What's causing this?

Question

I just received a copy of a grunt package to work on, but I'm new to grunt and am having trouble finding answers to a few things. The biggest issue is not knowing where the errors below are coming from - can someone tell me where this is coming from? Both of these files are in the same directory.

$ grunt
>> Local Npm module "grunt-contrib-clean" not found. Is it installed?
>> Local Npm module "grunt-contrib-concat" not found. Is it installed?
>> Local Npm module "grunt-contrib-copy" not found. Is it installed?
>> Local Npm module "grunt-contrib-cssmin" not found. Is it installed?
>> Local Npm module "grunt-contrib-handlebars" not found. Is it installed?
>> Local Npm module "grunt-contrib-jshint" not found. Is it installed?
>> Local Npm module "grunt-contrib-qunit" not found. Is it installed?
>> Local Npm module "grunt-contrib-uglify" not found. Is it installed?
>> Local Npm module "grunt-preprocess" not found. Is it installed?
>> Local Npm module "grunt-wrap" not found. Is it installed?
>> Local Npm module "grunt-debug-task" not found. Is it installed?
Warning: Task "clean" not found.  Use --force to continue.

Aborted due to warning.

$

And here is my package.json:

{
  "name": "baked-widget",
    "srcDirectory": "./src",
    "srcJavascript": "./src/js",
    "srcCss": "./src/css",
    "srcData": "./src/data",
    "testDirectory": "./test",
    "tgtDirectory": "./build",
    "installDirectory": "../com/public/widgets",
  "version": "4.2.0",
  "devDependencies": {
    "grunt": "~0.4",
    "grunt-contrib-clean": "~0.4.0",
    "grunt-contrib-concat": "~0.3.0",
    "grunt-contrib-copy": "~0.5.0",
    "grunt-contrib-cssmin": "~0.9.0",
    "grunt-contrib-handlebars": "~0.6",
    "grunt-contrib-jshint": "~0.8",
    "grunt-contrib-uglify": "~0.3",
    "grunt-contrib-qunit": "~0.4",
    "grunt-contrib-watch": "~0.5",
    "grunt-preprocess": "~4.0",
    "grunt-wrap": "~0.3",
    "grunt-debug-task": "~0.1.4"
  }
}

Answer 1

You probably haven't installed necessary packages locally. Try npm install (sudo npm install) to make sure you did that.