mongoose-uniqueslugs - Missing NodeJS Module in Modulus.io

I deployed NodeJS/ExpressJS web app in Modulus.io

In package.json, I already included the module mongoose-uniqueslugs:

"dependencies": {
    ...
    "mongoose": "3.6.11",
    "mongoose-uniqueslugs": "*",
    ...
}

In Modulus.io dashboard, I don't see the folder node_module but I think this is fine since the module is defined in package.json.

I deployed the app with modulus deploy CLI. No displayed error at all.

When browsing the app, it keeps on reloading, so I suspect the app have errors.

I viewed the logs with modulus project logs:

module.js:340
    throw err;
          ^
Error: Cannot find module 'mongoose-uniqueslugs'
    at Function.Module._resolveFilename (module.js:338:15)
    at Function.Module._load (module.js:280:25)
    at Module.require (module.js:364:17)
    at require (module.js:380:17)
    at Object.<anonymous> (/mnt/data/2/models/Category.js:2:27)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.require (module.js:364:17)
[2013-07-22T14:49:45.584Z] Application restarted with pid undefined

Line 2 of Category.js is:

 , mongooseUniqueSlugs = require('mongoose-uniqueslugs');