Deploying Node.js app to Heroku. Error NPM_CONFIG_LOGLEVEL=error

I am deploying my node.js application on heroku but when i run my app it shows me Application error and when i check my logs file i found NPM_CONFIG_LOGLEVEL=error

My package.json file is:

{
  "name": "wework-1",
  "version": "1.0.0",
  "description": "We Work Meteor, a job board and developer directory for Meteor specific work https://www.weworkmeteor.com",
  "main": "",
  "engines": {
    "node": "= 4.5.0",
    "npm": "= 3.9.6"
  },
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "lint": "eslint .",
    "pretest": "npm run lint --silent"
  },
  "repository": {
    "type": "git",
    "url": "git+https://github.com/rohitchaudhary701/wework-1.git"
  }
}

My logs file is:

-----> Node.js app detected
-----> Creating runtime environment

       NPM_CONFIG_LOGLEVEL=error
       NPM_CONFIG_PRODUCTION=true
       NODE_VERBOSE=false
       NODE_ENV=production
       NODE_MODULES_CACHE=true
-----> Installing binaries
       engines.node (package.json):  = 4.5.0
       engines.npm (package.json):   = 3.9.6

       Resolving node version = 4.5.0 via semver.io...
       Downloading and installing node 4.5.0...
       Resolving npm version = 3.9.6 via semver.io...
       Downloading and installing npm 3.9.6 (replacing version 2.15.9)...
-----> Restoring cache
       Loading 2 from cacheDirectories (default):
       - node_modules
       - bower_components (not cached - skipping)
-----> Building dependencies
       Installing node modules (package.json)
-----> Caching build
       Clearing previous node cache
       Saving 2 cacheDirectories (default):
       - node_modules
       - bower_components (nothing to cache)
-----> Build succeeded!
 !     This app may not specify any way to start a node process
       https://devcenter.heroku.com/articles/nodejs-support#default-web-process-type
-----> Discovering process types
       Procfile declares types     -> (none)
       Default types for buildpack -> web
-----> Compressing...
       Done: 12.7M
-----> Launching...
       Released v6
       https://whispering-cliffs-66861.herokuapp.com/ deployed to Heroku

App url is https://whispering-cliffs-66861.herokuapp.com/

via Rohit Chaudhary