If a pack is invalid, skip

update_dataset_index.py

@@ -99,7 +99,9 @@ def main():
                 stdout=subprocess.PIPE,
             )
             dataset_tree_id = process.stdout.decode('utf-8').split(" ")[0]
-            assert dataset_tree_id
+            if not dataset_tree_id:
+                log.error("Could not retrieve dataset_tree_id from pack %s, skipping", pack_file_name)
+                continue
 
             # Find blob ID of dataset.json in dataset tree.
             process = subprocess.run(