title: Nuxt generate show error: Cannot read property 'normalModuleFactory' of undefined
body: <p>Recently I upgrade Nuxt from 1.4.0 to 1.2.x and Vuetify from 1.0.9 to 1.2.x. After that npm run dev works fine. but when I run Nuxt generate I get below error. I am stuck on this error since last night and can't find any idea why it's occurring. Any guidance will be helpful. Thank in advance.</p>
  
  <pre><code>nuxt:build Generating files... +138ms
  nuxt:build Generating routes... +13ms
  nuxt:build Building files... +314ms
  
  ERROR
  
  TypeError: Cannot read property 'normalModuleFactory' of undefined
  
  - IgnorePlugin.js:96 IgnorePlugin.apply
  [vue]/[webpack]/lib/IgnorePlugin.js:96:18
  
  - Tapable.js:375 Compiler.apply
  [npm]/[nuxt]/[tapable]/lib/Tapable.js:375:16
  
  - webpack.js:33 webpack
  [npm]/[nuxt]/[webpack]/lib/webpack.js:33:19
  
  - builder.js:524 compilers.compilersOptions.map.compilersOption
  [npm]/[nuxt]/lib/builder/builder.js:524:24
  
  - Array.map
  
  - builder.js:523 Builder.webpackBuild
  [npm]/[nuxt]/lib/builder/builder.js:523:39
  
  - builder.js:168 Builder.build
  [npm]/[nuxt]/lib/builder/builder.js:168:16
  </code></pre>
  
  <p>package.json can be find <a href="https://gist.github.com/napestershine/13cc52f22fb16b9f13572afc23733fa8" rel="nofollow noreferrer">here.</a></p>
  
  <p>nuxt.config.js can be found <a href="https://gist.github.com/napestershine/41efa934d8c24cd98518cd3033553213" rel="nofollow noreferrer">here.</a></p>
  
  <p>I tried to dig about it, but it seems to be generated through webpack. So I updated to webpack 4 too. But still it's throwing this error.</p>
  
  <p>If you need any more details, I would be happy to provide.</p>