Prevent checkin errors where configuration not performed

[Alex]

Sometimes users install the plugin and try to use it directly before performing the configuration using the "Edit in office."
When then they try to save the changes, they get an exception of type "Object not set to a valid reference" (null-pointer exception).
If possible, we should warn users that they must complete the configuration of the plugin, or enter a descriptive text to resolve the probable cause of the error.