title: Unknown or duplicate parameter: NodeCommand
body: <p>I'm trying to deploy a Node.js API with Elastic beanstalk.</p>
  
  <p>I want to set the node command to start the app.</p>
  
  <p>This is my nodecommand.config:</p>
  
  <pre><code>option_settings:
    aws:elasticbeanstalk:container:nodejs:
      NodeCommand: "npm start"
  </code></pre>
  
  <p>This is my file structure:
  <a href="https://i.stack.imgur.com/BAamM.png" rel="noreferrer"><img src="https://i.stack.imgur.com/BAamM.png" alt="enter image description here"></a></p>
  
  <p>Whenever I try to run <code>eb deploy</code>, I get this error:</p>
  
  <pre><code>2020-05-13 19:03:44    INFO    Environment update is starting.      
  2020-05-13 19:03:48    ERROR   "option_settings" in one of the configuration files failed validation. More details to follow.
  2020-05-13 19:03:48    ERROR   Unknown or duplicate parameter: NodeCommand 
  2020-05-13 19:03:48    ERROR   Failed to deploy application.        
  
  ERROR: ServiceError - Failed to deploy application.
  </code></pre>