Suggested by Damir, a few additional methods on the BaseControl
class permit discovering all errors codes for available plugins.

Example output for the state of this commit:

        $ bin/omero errors
        123	     admin	NOT_WINDOWS	'Not Windows'
        200	     admin	     SETUP	'Error during service user set up:  (%s) %s'
        201	     admin	   RUNNING	'%s is already running. Use stop first'
        201	    server	 NO_CONFIG	'No --Ice.Config provided'
        202	     admin	NO_SERVICE	'%s service deleted.'
        300	     admin	BAD_CONFIG	'Bad configuration: No IceGrid.Node.Data property'
        400	     admin	WIN_CONFIG	'%s is not in this directory. Aborting...      ...'
        666	     admin	  NO_WIN32	'Could not import win32service and/or win32evtlogutil'

see: https://www.openmicroscopy.org/community/viewtopic.php?f=6&t=8676&p=20525#p20525