refactor: validate state object before retrieving dataframe

app.py

@@ -65,6 +65,7 @@ def _ensure_state(state) -> Dict[str, Any]:
 
 def _current_dataframe(state, filtered: bool = True) -> pd.DataFrame:
     """Return the filtered or raw dataframe from state."""
+    state = _ensure_state(state)
     key = "filtered_df" if filtered else "dataframe"
     df = state.get(key)
     if isinstance(df, pd.DataFrame):