Since error suppression was removed with the call to unlink() to make
sure that there are no previous test image files before testing for the
gs path, make sure that it exists first before deleting to prevent it
from throwing any errors.

It looks better (IMO) than using admin_setting_description and works in all
branches.

Jan Dageförde authored Mar 12, 2019 and Eloy Lafuente committed Mar 20, 2019

AMOS BEGIN
 CPY [block,core],[blockuserconfirmbutton,core_message]
AMOS END

The connection to the MongoDB server is checked on the creation and
deletion of a cache store instance. If the connection fails during
creation, the instance is set as not ready. Before deleting a instance,
a new cachestore_mongodb object is created, and connection checked.
There is no reason to check again the connection in the instance_deleted() method.