title: JPM not working
body: <p>I've just tried using <a href="https://developer.mozilla.org/en-US/Add-ons/SDK/Tools/jpm">JPM</a> for the first time, and I can't get anything to work.</p>
  
  <p>My index.js file looks like this:</p>
  
  <pre><code>const actionButton = require('sdk/ui/button/action');
  const TAG = "Addon Scratchpad / Index  ";
  
  console.log(TAG+'in index.js');
  
  var button = actionButton.ActionButton({
    id: "my-button",
    label: "my button",
    icon: {
      "16": "./tool-scratchpad-16.png",
      "32": "./tool-scratchpad-32.png"
    },
    onClick: function() {
      debugger;
      console.log(TAG+'button clicked');
    }
  });
  </code></pre>
  
  <p>The Folder structure is standard: <code>index.js</code> and <code>package.json</code> files and a <code>data</code> folder with the button <code>png</code> assets.</p>
  
  <p><code>jpm run</code> results in the browser opening. But no button is generated, there are no errors in the terminal or console, the addon debugger claims "This page has no sources."</p>
  
  <p><code>jpm test</code> results in no tests being run and no errors thrown.</p>
  
  <p><code>jpm run --debugger</code> doesn't launch the debugger. </p>
  
  <p>There were no errors during JPM installation (I uninstalled and reinstalled globally to check). </p>
  
  <p>index.js is in the root of the directory, which isn't what I'm used to, but this is <a href="https://developer.mozilla.org/en-US/Add-ons/SDK/Tutorials/Getting_Started_%28jpm%29">apparently normal</a>: </p>
  
  <blockquote>
    <p>your main file is "index.js", and it is found directly in your add-on's root.</p>
  </blockquote>
  
  <p>If I unpackage the xpi it looks normal. If I install it by dragging to Firefox the same issues persist.</p>
  
  <p>I'm stumped. Any ideas why I can't get it to work?</p>