Update packages/bigframes/bigframes/series.py

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: shuoweil

packages/bigframes/bigframes/series.py

@@ -2283,7 +2283,7 @@ def to_frame(self, name: blocks.Label = None) -> bigframes.dataframe.DataFrame:
         provided_name = name if name is not None else self.name
         # To be consistent with Pandas, it assigns 0 as the column name if missing. 0 is the first element of RangeIndex.
         column_names: List[blocks.Label]
-        if provided_name is None or pandas.isna(cast(Any, provided_name)):
+        if provided_name is None or pandas.isna([cast(Any, provided_name)])[0]:
             column_names = [0]
         else:
             column_names = [provided_name]