title: Grunt build not working in Yo Angular
body: <p>I build a Angular App with Yo angular-genertor,</p>
  
  <p>I was building the app with Grunt Build fine, then I added Bootstrap 3 and also npm install grunt-bower-install </p>
  
  <p>I added these lines to the Grunt file</p>
  
  <pre><code>module.exports = function (grunt) {
  
  
    require('load-grunt-tasks')(grunt);
  
    require('time-grunt')(grunt);
  
    //ADDED THIS LINE
    grunt.loadNpmTasks('grunt-bower-install');
  
    grunt.initConfig({
  
      yeoman: {
        // configurable paths
        app: require('./bower.json').appPath || 'app',
        dist: 'dist'
      },
       //ADDED THESE LINES
      'bower-install': {
          target: {
              src: [
                'app/index.html'
              ],
  
            }
          },
  </code></pre>
  
  <p>I have removed these line however!</p>
  
  <p>Now Grunt Build is throwing this error</p>
  
  <pre><code>Running "bowerInstall:app" (bowerInstall) task
  Warning: Cannot read property 'main' of undefined Use --force to continue.
  
  Aborted due to warnings.
  </code></pre>
  
  <p>I do know what to do or even where to start?</p>