fix: guard type of states names in info.json (#123)

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: shuheng-liu

src/opentau/scripts/visualize_dataset.py

@@ -222,6 +222,14 @@ def visualize_dataset(
     if joint_names is None:
         joint_names = dataset.meta.info.get("features", {}).get("observation.state", {}).get("names", [])
 
+    # Guard against invalid state names from info.json (ensure it's a list of strings)
+    if not (isinstance(joint_names, list) and all(isinstance(name, str) for name in joint_names)):
+        logging.warning(
+            "Invalid joint_names type in info.json: %s. Expected list of strings. Using numeric indices instead.",
+            type(joint_names),
+        )
+        joint_names = []
+
     if urdf:
         rr.log_file_from_path(urdf, static=True)
         urdf_tree = rr.urdf.UrdfTree.from_file_path(urdf)