Makes sure the guest user context exists when fetching
the recommended modules. If the context does not exist
an exception is being thrown describing the problem.
When plugins are removed from disk, an exception is thrown when
calling component_callback_exists.
This exception should be catched here in order to load properly
the activity chooser (otherwise, the exception will be displayed
and no activity will appear).
Returns all content items which are provided by the plugin, irrespective
of whether or not a user can see an item in a particular course. This is
used to generate a global list of content items, allowing for admin
level features to be added.
