Editor unable to parse Javascript file

Attempting to open the javascript file scripts.js causes a parsing error.

NullPointerException: The content parameter cannot be null

It is a cut down version of a much larger file, but this file seems to trigger the error everytime I attempt to open it and set it to be the active window.

The navigator window does appear to show the correct results, but in the complete version of the file, the navigator window stops working and NetBeans just goes into an endless loop.