If you setup an installation with two languages and configure two Administration Portal site accesses so that one of them only has access to contents in one language, eZ Publish will present a fatal error message if you attempt to edit an object translated into the other language.

Steps to reproduce

Install a fresh eZP 4.4 or 4.5 with two languages: English and French
Configure two extra site accesses. one for English Admin, one for French Admin.
Set it up so that only English language is available to English Admin ( ShowUntranslatedObjects=disabled)
Using the main Admin Portal (that holds access to all languages):
Create a folder under root, name it "Versions"
Create a couple of folders under "Versions". One in English (name it "English") and one in French (name it "French")
Create an article within folder Versions/English. Publish it. Add a second location for it under Versions/French. Translate the object to French.
(You will be able to see an article in English within Versions/English folder and another in French within Versions/French.
Login English Admin Portal.
You will only see folder Versions/English (since ShowUntranslatedObjects=disabled)
Edit the article and publish it.
eZ will crash with a fatal error. The message below will be added to apache's error_log

Call to a member function attribute() on a non-object in /var/www/ez45_1/kernel/content/ezcontentoperationcollection.php on line 257