Pick up data when editor is destroyed

This is not directly related to this module but I had no luck in the CKEditor forum.

I'm working on a CKEditor plugin which needs to transform data depending on if the editor is enabled or not.
During init I use "afterInit" which works fine. When the editor is destroyed I am using:
editor.on('destroy', function(event) { ... });

When I call editor.getData() or editor.setData() I see this in the console:
i.contentWindow is null
http://localhost/drupal/sites/all/modul ... ditor.js?I
Line 18

I've also tried with: event.editor.getData() - Same error message.

So, while the data is inside the editor I would like to render the code as HTML, and when editor is destroyed I would like to return the code to the textarea.