Event becomes un-editable

[gilran]

I created the event "The Killing Times".
I don't know what exactly I did, but at some point it became un-editable.
When I click the update, there's a js error:
rollbar.min.js:1 Uncaught TypeError: Cannot read property 'value' of null

The סידור חדר field does not appear in the form. I think this happened at the same time that the event became un-editable.