admin/includes/ceon_uri_mapping_javascript.php was probably wrong, but I think I may have gone back and recopied in the v5.1.0 file, before you asked this question.
Now, when I remove the requested lines from admin/includes/javascript_loader.php Im still retaining the ability to change the file name in the admin product page.
I noticed that the error log message hadnt been produced for a couple of hours.

I might just be ok now, with no errors of any kind.