type: Fix type erroring out (#7950)

Author: hoxbro

panel/widgets/tables.py

@@ -679,6 +679,7 @@ def _process_df_and_convert_to_cds(self, df: pd.DataFrame) -> tuple[pd.DataFrame
         df = self._filter_dataframe(df, header_filters=False)
         if df is None:
             return [], {}
+        indexes: list[Any]
         if isinstance(self.value.index, pd.MultiIndex):
             indexes = [
                 f'level_{i}' if n is None else n