provide default name for log file in launch service constructor

Signed-off-by: Tanishq Chaudhary <[email protected]>

Author: Tanishq30052002

launch/launch/launch_service.py

@@ -56,7 +56,7 @@ def __init__(
         argv: Optional[Iterable[Text]] = None,
         noninteractive: bool = False,
         debug: bool = False,
-        log_file_name: Optional[Text] = None
+        log_file_name = 'launch'
     ) -> None:
         """
         Create a LaunchService.
@@ -69,8 +69,6 @@ def __init__(
         # Setup logging and debugging.
         launch.logging.launch_config.level = logging.DEBUG if debug else logging.INFO
         self._log_file_name = log_file_name
-        if self._log_file_name is None:
-            self._log_file_name = 'launch'
         # Ensure the log file name ends with `.log`
         if not self._log_file_name.endswith('.log'):
             self._log_file_name += '.log'