title: webpack-cli can't find webpack module
body: <p>i have installed webpack globally and when i run <code>webpack</code> it says </p>
  
  <pre><code>One CLI for webpack must be installed. These are recommended choices, delivered as separate packages:
   - webpack-cli (https://github.com/webpack/webpack-cli)
     The original webpack full-featured CLI.
  We will use "npm" to install the CLI via "npm install -D".
  Do you want to install 'webpack-cli' (yes/no):
  </code></pre>
  
  <p>and I say yes, the webpack-cli seems to be installed correctly but i got an error message that says </p>
  
  <pre><code>{ Error: Cannot find module 'webpack'
      at Function.Module._resolveFilename (internal/modules/cjs/loader.js:582:15)
      at Function.Module._load (internal/modules/cjs/loader.js:508:25)
      at Module.require (internal/modules/cjs/loader.js:637:17)
      at require (C:\Users\TOSHIBA\node_modules\v8-compile-cache\v8-compile-cache.js:159:20)
      at Object.&lt;anonymous&gt; (C:\Users\TOSHIBA\node_modules\webpack-cli\bin\convert-argv.js:7:24)
      at Module._compile (C:\Users\TOSHIBA\node_modules\v8-compile-cache\v8-compile-cache.js:178:30)
      at Object.Module._extensions..js (internal/modules/cjs/loader.js:712:10)
      at Module.load (internal/modules/cjs/loader.js:600:32)
      at tryModuleLoad (internal/modules/cjs/loader.js:539:12)
      at Function.Module._load (internal/modules/cjs/loader.js:531:3)
      at Module.require (internal/modules/cjs/loader.js:637:17)
      at require (internal/modules/cjs/helpers.js:22:18)
      at yargs.parse (C:\Users\TOSHIBA\node_modules\webpack-cli\bin\cli.js:228:14)
      at Object.parse (C:\Users\TOSHIBA\node_modules\yargs\yargs.js:567:18)
      at C:\Users\TOSHIBA\node_modules\webpack-cli\bin\cli.js:206:8
      at Object.&lt;anonymous&gt; (C:\Users\TOSHIBA\node_modules\webpack-cli\bin\cli.js:505:3)
      at Module._compile (internal/modules/cjs/loader.js:701:30)
      at Object.Module._extensions..js (internal/modules/cjs/loader.js:712:10)
      at Module.load (internal/modules/cjs/loader.js:600:32)
      at tryModuleLoad (internal/modules/cjs/loader.js:539:12)
      at Function.Module._load (internal/modules/cjs/loader.js:531:3)
      at Module.require (internal/modules/cjs/loader.js:637:17)
      at require (internal/modules/cjs/helpers.js:22:18)
      at runCommand.then (C:\Users\TOSHIBA\AppData\Roaming\npm\node_modules\webpack\bin\webpack.js:143:5)
      at process._tickCallback (internal/process/next_tick.js:68:7) code: 'MODULE_NOT_FOUND' }
  </code></pre>
  
  <p>what is possibility goes wrong?</p>