title: Can't add plugin run/debug configuration in IntelliJ IDEA
body: <p>I want to modify an existing IntelliJ IDEA plugin as a step toward building my own. I chose <a href="https://github.com/jmulieri/front-end-alignment" rel="noreferrer">Front End Alignment</a>, opened it in IntelliJ IDEA, added the IntelliJ Community Edition SDK, and built the project successfully. But when I try to add a Plugin Run/Debug Configuration (to verify that I can debug a plugin) the "Use classpath of module" dropdown contains only "[None]", and I get:</p>
  
  <pre><code>Run Configuration Error: No plugin module specified for configuration
  </code></pre>
  
  <p>Project Structure > Project Settings > Modules shows that <code>front-end-alignment</code> is a known module.</p>
  
  <p>How can I run this sample plugin in the debugger?</p>