user object notification on /message/index.php

/message/index.php is saying...

Missing email property in $user object, this is a performance problem that needs to be fixed by a developer. Please use user_picture::fields() to get the full list of required fields.

• line 356 of /lib/outputcomponents.php: call to debugging()
• line 1686 of /lib/outputrenderers.php: call to user_picture->__construct()
• line 1550 of /message/lib.php: call to core_renderer->user_picture()
• line 349 of /message/lib.php: call to message_print_contactlist_user()
• line 95 of /message/lib.php: call to message_print_contacts()
• line 205 of /message/index.php: call to message_print_contact_selector()