Hi,

In Oracle, plain_site, when i finish the signup of a new user, i get the following warning message in debug:

array_key_exists() [<a href='function.array-key-exists'>function.array-key-exists</a>]: The second argument should be either an array or an object in /data1/www/apache2php52/ezporacle/.run/kernel/classes/ezpersistentobject.php on line 123

Steps to reproduce

Enter ezpublish in plain_site
click the "login" button
Click the "Sign up" button
fill in the user fields, using an *existent* mail
click on "register" button

After the last step, the warning appears