code: def test_struct_iterate_error():
      s = cudf.Series(
          [{"f2": {"a": "sf21"}, "f1": "a"}, {"f1": "sf12", "f2": None}]
      )
      with pytest.raises(TypeError):
          iter(s.struct)
  
imports: import numpy
  import pandas
  import pyarrow
  import pytest
  import cudf
  from cudf.core.dtypes import StructDtype
  from cudf.testing._utils import DATETIME_TYPES, TIMEDELTA_TYPES, assert_eq
label_desc: Use image node_id 25 for calling a global function with example usage: test_struct_iterate_error() without return types