Make message in log if local_subscriber_ids file is missing more informative

hblink.py

@@ -60,7 +60,7 @@ from functools import partial, partialmethod
 
 import ssl
 
-from os.path import isfile, getmtime
+from os.path import isfile, getmtime, exists
 from urllib.request import urlopen
 
 import shutil
@@ -1474,6 +1474,7 @@ def mk_aliases(_config):
             except IOError as g:
                 logger.info('(ALIAS) ID ALIAS MAPPER: couldn\'t make backup copy of talkgroup_ids file %s',g)
 
+    if exists(_config['ALIASES']['PATH'] + _config['ALIASES']['LOCAL_SUBSCRIBER_FILE']):
         try:
             local_subscriber_ids = mk_id_dict(_config['ALIASES']['PATH'], _config['ALIASES']['LOCAL_SUBSCRIBER_FILE'])
         except Exception as e:
@@ -1489,6 +1490,8 @@ def mk_aliases(_config):
                     shutil.copy(_config['ALIASES']['PATH'] + _config['ALIASES']['LOCAL_SUBSCRIBER_FILE'],_config['ALIASES']['PATH'] + _config['ALIASES']['LOCAL_SUBSCRIBER_FILE'] + '.bak')
                 except IOError as g:
                     logger.info('(ALIAS) ID ALIAS MAPPER: couldn\'t make backup copy of local_subscriber_ids file %s',g)
+    else:
+        logger.info('(ALIAS) ID ALIAS MAPPER: local subscriber file does not exist and is optional, skipping. ')
 
     try:
         server_ids = mk_server_dict(_config['ALIASES']['PATH'], _config['ALIASES']['SERVER_ID_FILE'])