title: Webpack doesn't find a module that actually exists
body: <p>I'm in trouble, I just did <code>npm uninstall react-bootstrap</code> and then <code>npm install react-bootstrap</code> and webpack cannot load this module anymore.</p>
  
  <p>I launch webpack like this : </p>
  
  <pre><code>/var/www/cloud/node_modules/.bin/webpack --config webpack.config.js --watch --display-error-details
  </code></pre>
  
  <p>And here is the error, it just can't find the <code>package.json</code> inside <code>react-bootstrap</code>: </p>
  
  <pre><code>ERROR in ./core/static/core/js/modules/dashboard/admin/Customer.js
  Module not found: Error: Cannot resolve module 'react-bootstrap' in /var/www/cloud/core/static/core/js/modules/dashboard/admin
  resolve module react-bootstrap in /var/www/cloud/core/static/core/js/modules/dashboard/admin
    looking for modules in /var/www/cloud/node_modules
      resolve 'file' react-bootstrap in /var/www/cloud/node_modules
        resolve file
          /var/www/cloud/node_modules/react-bootstrap is not a file
          /var/www/cloud/node_modules/react-bootstrap.js doesn't exist
          /var/www/cloud/node_modules/react-bootstrap.jsx doesn't exist
      resolve 'file' or 'directory' /var/www/cloud/node_modules/react-bootstrap
        resolve file
          /var/www/cloud/node_modules/react-bootstrap is not a file
          /var/www/cloud/node_modules/react-bootstrap.js doesn't exist
          /var/www/cloud/node_modules/react-bootstrap.jsx doesn't exist
        resolve directory
          use lib/index.js from package.json
            resolve 'file' or 'directory' lib/index.js in /var/www/cloud/node_modules/react-bootstrap
              resolve file
                /var/www/cloud/node_modules/react-bootstrap/lib/index.js doesn't exist
                /var/www/cloud/node_modules/react-bootstrap/lib/index.js.js doesn't exist
                /var/www/cloud/node_modules/react-bootstrap/lib/index.js.jsx doesn't exist
              resolve directory
                /var/www/cloud/node_modules/react-bootstrap/lib/index.js/package.json doesn't exist (directory description file)
                /var/www/cloud/node_modules/react-bootstrap/lib/index.js doesn't exist (directory default file)
          directory default file index
            resolve file index in /var/www/cloud/node_modules/react-bootstrap
              /var/www/cloud/node_modules/react-bootstrap/index doesn't exist
              /var/www/cloud/node_modules/react-bootstrap/index.js doesn't exist
              /var/www/cloud/node_modules/react-bootstrap/index.jsx doesn't exist
  </code></pre>
  
  <p>That's really odd, my <code>package.json</code> looks like :</p>
  
  <pre><code>{
    "name": "cloud",
    "version": "1.0.0",
    "description": "hehe",
    "main": "gulp.js",
    "scripts": {
      "dev": "webpack-dev-server --devtool eval --progress --colors --content-base build"
    },
    "repository": {
      "type": "git",
      "url": ""
    },
    "author": "",
    "license": "",
      "dependencies": {
      "anima": "^0.4.0",
      "immutable": "^3.7.4",
      "imports-loader": "^0.6.4",
      "moment": "^2.10.3",
      "react-bootstrap": "^0.23.7",
      "react-google-recaptcha": "^0.3.2",
      "react-paginate": "^0.1.31",
      "script-loader": "^0.6.1",
      "underscore": "^1.8.3"
    },
    "devDependencies": {
      "babel": "^5.5.6",
      "babel-core": "^5.5.6",
      "babel-loader": "^5.1.4",
      "css-loader": "^0.15.1",
      "node-libs-browser": "^0.5.2",
      "react-hot-loader": "^1.2.7",
      "style-loader": "^0.12.3",
      "webpack": "^1.9.10",
      "webpack-bundle-tracker": "0.0.51"
    }
  }
  </code></pre>
  
  <p>And my webpack config : </p>
  
  <pre><code>var path = require("path");
  var webpack = require('webpack');
  var BundleTracker = require('webpack-bundle-tracker'); 
  var bower_dir = __dirname + '/components/bower_components/';
  var node_modules_dir = path.resolve(__dirname, 'node_modules');
  
  module.exports = {
      context: __dirname,
      entry: {
          app: [ './core/static/core/js/main.js', ],
                vendor: ['react', 'react-router', 'react-bootstrap', 'react-google-recaptcha', 'react-spinkit'],  
      },    
      output: {
          path: path.resolve('./static/bundles/'),
          filename: 'bundle.js',
          publicPath:''           
      },  
      externals: {
          // require("jquery") is external and available
          //  on the global var jQuery
          "jquery": "jQuery",
          "utils": "utils"
      }, 
      plugins: [new BundleTracker({filename: './webpack-stats.json'}),
                new webpack.optimize.CommonsChunkPlugin(/* chunkName= */"vendor", /* filename= */"vendor.bundle.js"),   
                /*new webpack.ProvidePlugin({
              $: "jquery",
              jQuery: "jquery",
              "window.jQuery": "jquery"
          })*/],
                module: {
                    loaders: [{ test: /\.jsx?$/, exclude: node_modules_dir, loaders: ['babel']}, // to transform JSX into JS
                              { test: require.resolve("jquery"), loader: "imports?jQuery=jquery" },
                              { test: /\.json$/, loader: "json" },
                              { test: /\.css$/, loader: "style-loader!css-loader?root=." }],
                },
                resolve: {
                    modulesDirectories: ['node_modules', 'bower_components'],
                    extensions: ['', '.js', '.jsx']
                },
  };
  </code></pre>
  
  <p>Plus, the folder <code>react-bootstrap</code> do exists in my <code>node_modules</code>.</p>
  
  <p>My tree is like this :</p>
  
  <pre><code>webpack.config.js
  node_modules
  package.json
  </code></pre>
  
  <p>I'm totally lost...</p>