Make last_error_msg a string, not None

Author: timvaillancourt

mongodb_consistent_backup/Main.py

@@ -49,7 +49,7 @@ def __init__(self, prog_name="mongodb-consistent-backup"):
         self.logger                   = None
         self.current_log_file         = None
         self.backup_log_file          = None
-        self.last_error_msg           = None
+        self.last_error_msg           = ''
 
         try:
             self.setup_config()