The 'list_regions' shell command gets a list of regions for a given table and then prints them and some attributes such as the server where they are located, current request count, data locality, and such.
However if a region is in transition the command might fail with
ERROR: undefined method `getDataLocality' for nil:NilClass
and there may be other ways this can happen. Protect against use of nil references and just display what we can.