After removing the user that created a Content Object, after going to "Details" tab of this Content Object in the Platform UI, "Last contributor" field results in the following error:

An error occurred while loading the last contributor.

The error is shown even if the person that updated the content last still exists (and differs from the Creator).

Steps to reproduce

1. Create a new installation of eZ Platform.
2. In the Platform UI, create new User in the "Editors" User Group with login "test_editor".
3. Log out and log in again as "test_editor".
4. Under "Home", create new Article Content Object named "Test Article".
5. Log out and log in again as "admin".
6. Edit and publish a new version of "Test Article".
7. Go to the "Details" tab for "Test Article".Confirm that there is "Administrator User" in the "Last contributor" field.
8. Delete User "test_editor".
9. Go to the "Details" tab for "Test Article". You will notice the error mentioned above for the "Last contributor" field.

NOTE: not having permissions to read the creator's data will probably also result in the same error. The creator probably doesn't have to be deleted.