fix: no-ops upload/download methods (#2571)

* fix: Add exception to handle unconfigured upload/download methods

* docformatter fix

* no-ops

* no-ops 1

src/ansys/fluent/core/session.py

@@ -281,7 +281,8 @@ def upload(self, file_name: str):
         file_name : str
             Name of the local file to upload to the server.
         """
-        return self._file_transfer_service.upload_file(file_name)
+        if self._file_transfer_service:
+            return self._file_transfer_service.upload_file(file_name)
 
     def download(self, file_name: str, local_directory: Optional[str] = "."):
         """Download a file from the server.
@@ -293,7 +294,8 @@ def download(self, file_name: str, local_directory: Optional[str] = "."):
         local_directory : str, optional
             Local destination directory. The default is the current working directory.
         """
-        return self._file_transfer_service.download_file(file_name, local_directory)
+        if self._file_transfer_service:
+            return self._file_transfer_service.download_file(file_name, local_directory)
 
     def __enter__(self):
         return self