Steps to reproduce the issue

Log in the front end as super user.
Edit and save a module.
In the back end, in the Latest Actions box, click on the All Modules link.

User admin updated the module All Modules

Actual result

Error: 0 Call to undefined method stdClass::execute()

In PHP error log:

PHP Warning: Creating default object from empty value in \administrator\components\com_config\config.php on line 28

System information (as much as possible)

staging