title: Yarn run build -- no such file or directory: 'run'
body: <p>I am using Ruby on Rails 5 and following the steps here to implement CKEditor 5: <a href="https://ckeditor.com/docs/ckeditor5/latest/builds/guides/integration/installing-plugins.html" rel="nofollow noreferrer">https://ckeditor.com/docs/ckeditor5/latest/builds/guides/integration/installing-plugins.html</a></p>
  <p>I have successfully git cloned, ran npm install, updated the <code>ckeditor.js</code> file to include the Alignment module, but now I cannot run <code>yarn run build</code> as per the instructions:</p>
  <pre><code>root@45899dc31ad7:/myapp/node_modules/ckeditor5/packages/ckeditor5-build-classic# yarn run build
  00h00m00s 0/0: : ERROR: [Errno 2] No such file or directory: 'run'
  </code></pre>
  <p>What am I doing wrong? If I do an <code>ls</code>, it appears that I'm in the correct directory:</p>
  <pre><code>root@45899dc31ad7:/myapp/node_modules/ckeditor5/packages/ckeditor5-build-classic# ls -lh
  total 468K
  -rw-r--r--   1 root root 128K Dec 24 20:56 CHANGELOG.md
  -rw-r--r--   1 root root  215 Dec 24 20:56 CONTRIBUTING.md
  -rw-r--r--   1 root root 1.3K Dec 24 20:56 LICENSE.md
  -rw-r--r--   1 root root 3.2K Dec 24 20:56 README.md
  drwxr-xr-x   3 root root 4.0K Dec 24 20:56 build
  drwxr-xr-x 496 root root  20K Dec 24 20:58 node_modules
  -rw-r--r--   1 root root 283K Dec 24 20:58 package-lock.json
  -rw-r--r--   1 root root 2.4K Dec 24 20:58 package.json
  drwxr-xr-x   2 root root 4.0K Dec 24 20:56 sample
  drwxr-xr-x   2 root root 4.0K Dec 24 20:56 src
  drwxr-xr-x   3 root root 4.0K Dec 24 20:56 tests
  -rw-r--r--   1 root root 2.0K Dec 24 20:56 webpack.config.js
  </code></pre>
  <p>Does this mean I'm using a wrong version of <code>yarn</code> or something by chance?</p>