Trying to get property of non-object dans content_lock_user_logout()

Context : The website is totally private, so the access to the homepage show "Acces denied", and the login form. I use autologout module to log my user out after a period of inactivity (one hour).

At the top of the page, i have this error when i'm logged out automatically :

Notice : Trying to get property of non-object dans content_lock_user_logout() (ligne 471 dans /data/preprod/thales-project/sites/all/modules/contrib/content_lock/content_lock.module).

It occures very often because the automatic logout works each time we come back to the website after more than one hour. And after one page refresh, the message is gone.

In the code, i can see that $account->uid is used. It seems that $account is not available to get the uid. Maybe $account should be tested before trying to get the uid property ?