Merge branch 'user/michel-aractingi/2025_06_30_dataset_v3' into user/michel-aractingi/2025-9-9-incremental_parquet_writing

Author: michel-aractingi

src/lerobot/datasets/lerobot_dataset.py

@@ -1298,7 +1298,8 @@ def clear_episode_buffer(self, delete_images: bool = True) -> None:
             if self.image_writer is not None:
                 self._wait_image_writer()
             episode_index = self.episode_buffer["episode_index"]
-            episode_index = episode_index.item() if episode_index.size == 1 else episode_index[0]
+            if isinstance(episode_index, np.ndarray):
+                episode_index = episode_index.item() if episode_index.size == 1 else episode_index[0]
             for cam_key in self.meta.camera_keys:
                 img_dir = self._get_image_file_dir(episode_index, cam_key)
                 if img_dir.is_dir():

src/lerobot/datasets/v30/convert_dataset_v21_to_v30.py

@@ -204,7 +204,8 @@ def convert_data(root: Path, new_root: Path, data_file_size_in_mb: int):
             paths_to_cat.append(ep_path)
             continue
 
-        concat_data_files(paths_to_cat, new_root, chunk_idx, file_idx, image_keys)
+        if paths_to_cat:
+            concat_data_files(paths_to_cat, new_root, chunk_idx, file_idx, image_keys)
 
         # Reset for the next file
         size_in_mb = ep_size_in_mb