improve error handling for the case the database can not be reached

src/ez_lan_manager/services/DatabaseService.py

@@ -21,6 +21,9 @@ logger = logging.getLogger(__name__.split(".")[-1])
 class DuplicationError(Exception):
     pass
 
+class NoDatabaseConnectionError(Exception):
+    pass
+
 class DatabaseService:
     def __init__(self, database_config: DatabaseConfiguration) -> None:
         self._database_config = database_config
@@ -37,8 +40,8 @@ class DatabaseService:
                 database=self._database_config.db_name
             )
         except mariadb.Error as e:
-            logger.fatal(f"Error connecting to database: {e}")
-            sys.exit(1)
+            logger.error(f"Error connecting to database: {e}")
+            raise NoDatabaseConnectionError
 
     def _get_cursor(self) -> Cursor:
         return self._connection.cursor()