title: Nuxtjs with scrollmagic gives me "window is not defined"
body: <p>I want to use scrollmagic with nuxtjs.</p>
  
  <p>I installed scrollmagic via npm. </p>
  
  <pre><code>npm install scrollmagic
  </code></pre>
  
  <p>In my nuxt.config.js file i added </p>
  
  <pre><code>build: {
      vendor: ['scrollmagic']
  },
  </code></pre>
  
  <p>And in my pages/index.vue file i simply imported it.</p>
  
  <pre><code>import ScrollMagic from 'scrollmagic'
  </code></pre>
  
  <p>But this results only in this error </p>
  
  <blockquote>
    <p>[vue-router] Failed to resolve async component default:
    ReferenceError: window is not defined [vue-router] uncaught error
    during route navigation: ReferenceError: window is not defined
        at C:\pathto\node_modules\scrollmagic\scrollmagic\uncompressed\ScrollMagic.js:37:2
        at C:\pathto\node_modules\scrollmagic\scrollmagic\uncompressed\ScrollMagic.js:22:20
        at Object. (C:\pathto\node_modules\scrollmagic\scrollmagic\uncompressed\ScrollMagic.js:27:2)</p>
  </blockquote>
  
  <p>How can i fix this?</p>