title: What is the source of Meteor 1.5 updgrade Error with imports, and how to fix it
body: <p>Having issues with the new release of Meteor 1.5</p>
  
  <p>After upgrading an existing Meteor app the following errors were thrown
  <a href="https://forums.meteor.com/t/meteor-1-5-update-imports-promise-server-error-on-build/36905/5" rel="nofollow noreferrer">(Original Post on Meteor forums)</a></p>
  
  <pre><code>=&gt; Started proxy.                                                                        
  /Users/&lt;user&gt;/.meteor/packages/coffeescript/.1.12.3_1.ph1kh6++os+web.browser+web.cord
  ova/plugin.compileCoffeescript.os/npm/node_modules/meteor/promise/node_modules/meteor-pro
  mise/promise_server.js:190                                                               
        throw error;                                                                       
        ^                                                                                  
  
  TypeError: Path must be a string. Received undefined                                     
      at assertPath (path.js:8:11)                                                         
      at Object.posix.relative (path.js:496:3)
  </code></pre>
  
  <p>Removing all non-essential and test removing coffeescript package, the error persists. Have seen other instances of the error reported. </p>