added wandb.run_id to allow resuming without wandb log; updated log m… (#841)

Co-authored-by: Simon Alibert <75076266+aliberts@users.noreply.github.com>

lerobot/configs/train.py

@@ -79,7 +79,9 @@ class TrainPipelineConfig(HubMixin):
             # The entire train config is already loaded, we just need to get the checkpoint dir
             config_path = parser.parse_arg("config_path")
             if not config_path:
-                raise ValueError("A config_path is expected when resuming a run.")
+                raise ValueError(
+                    f"A config_path is expected when resuming a run. Please specify path to {TRAIN_CONFIG_NAME}"
+                )
             if not Path(config_path).resolve().exists():
                 raise NotADirectoryError(
                     f"{config_path=} is expected to be a local path. "