code: def test_woodwork_dataframe_without_name_errors(es):
      new_es = EntitySet()
  
      new_df = es["sessions"].ww.copy()
      new_df.ww._schema.name = None
  
      assert new_df.ww.name is None
  
      error = (
          "Cannot add a Woodwork DataFrame to EntitySet without a name"
      )
      with pytest.raises(ValueError, match=error):
          new_es.add_dataframe(new_df)
  
imports: from datetime import datetime
  import numpy
  import pandas
  import pytest
  from woodwork.exceptions import TypeConversionError
  from woodwork.logical_types import Boolean, Categorical, Datetime, Double, Integer, NaturalLanguage
  from featuretools.entityset.entityset import LTI_COLUMN_NAME, EntitySet
  from featuretools.tests.testing_utils import to_pandas
  from featuretools.utils.gen_utils import Library, import_or_none, is_instance
label_desc: Use image node_id 29 for calling a global function with example usage: test_woodwork_dataframe_without_name_errors(es) without return types