title: google chrome bug?
body: <p>this message appears all the time in chrome developer tool's console:</p>
  
  <pre><code>Port error: Could not establish connection. Receiving end does not exist. miscellaneous_bindings:232
  chromeHidden.Port.dispatchOnDisconnect miscellaneous_bindings:232
  Error in event handler for 'undefined': Cannot read property 'instanceId' of undefined TypeError: Cannot read property 'instanceId' of undefined
      at [object Object].&lt;anonymous&gt; (chrome-extension://mgijmajocgfcbeboacabfgobmjgjcoja/content_js_min.js:2:372)
      at chrome-extension://mgijmajocgfcbeboacabfgobmjgjcoja/content_js_min.js:1:182
      at miscellaneous_bindings:276:11
      at [object Object].dispatch (event_bindings:203:41)
      at Object.&lt;anonymous&gt; (miscellaneous_bindings:235:27) event_bindings:207
  chrome.Event.dispatch event_bindings:207
  chromeHidden.Port.dispatchOnDisconnect miscellaneous_bindings:235
  </code></pre>
  
  <p>is this a bug in chrome or there is something wrong in my chrome installation?</p>