Mongoose: Error cannot find module debug

Question

I'm building a basic MEAN webapp and am new to the stack. I have the front end running, but as soon as I add the following lines to app.js:

var mongoose = require('mongoose');
require('./models/test');
mongoose.connect('mongodb://localhost:3000/design-data-test');

I get the following error in terminal:

Error: Cannot find module 'debug'
    at Function.Module._resolveFilename (module.js:336:15)
    at Function.Module._load (module.js:278:25)
    at Module.require (module.js:365:17)
    at require (module.js:384:17)
    at Object.<anonymous> (/Users/username/node_modules/mongoose/node_modules/mquery/lib/mquery.js:11:13)
    at Module._compile (module.js:460:26)
    at Object.Module._extensions..js (module.js:478:10)
    at Module.load (module.js:355:32)
    at Function.Module._load (module.js:310:12)
    at Module.require (module.js:365:17)
    at require (module.js:384:17)

And all of my front end code stops running. Mongodb is running on the default port.

How would I go about resolving this error?

Answer 1

For future visitors: You are probably missing a dependency. Make sure you run this first:

npm install

... before you run your app with npm start or node <app>

Answer 2

I think this may happen if you have a child dependency on debug through another package (for example express or mongoose) but you did not provide the dependencies' package.json files with the deployed application which makes node.js unable to locate debug.