if file name not provided in function, use user provided name

Author: izzaaaatanishq

launch/launch/logging/__init__.py

@@ -322,7 +322,7 @@ def get_log_file_path(self, file_name='launch.log'):
         file_name = self.file_name
         return os.path.join(self.log_dir, file_name)
 
-    def get_log_file_handler(self, file_name='launch.log'):
+    def get_log_file_handler(self, file_name=None):
         """
         Get the logging handler to a log file.
 
@@ -333,6 +333,8 @@ def get_log_file_handler(self, file_name='launch.log'):
         :return: the logging handler associated to the file (always the same
         once constructed).
         """
+        if file_name is None:
+            file_name = self.file_name
         if file_name not in self.file_handlers:
             file_path = self.get_log_file_path(file_name)
             factory = self.log_handler_factory