code: def test_crashes_with_empty_feature_value_and_no_default(self):
      tokenizer = SpacyTokenizer(parse=True)
      tokens = tokenizer.tokenize("This is a sentence.")
      tokens = [t for t in tokens] + [Token("</S>")]
      vocab = Vocabulary()
      vocab.add_token_to_namespace("ROOT", namespace="dep_labels")
      vocab.add_token_to_namespace("NONE", namespace="dep_labels")
      indexer = SingleIdTokenIndexer(
          namespace="dep_labels", feature_name="dep_"
      )
      with pytest.raises(ValueError):
          indexer.tokens_to_indices([tokens[-1]], vocab)
  
imports: from collections import defaultdict
  from dataclasses import dataclass
  import pytest
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.data import Token, Vocabulary
  from allennlp.data.token_indexers import SingleIdTokenIndexer
  from allennlp.data.tokenizers import SpacyTokenizer
label_desc: Use image node_id 6 for calling the TestSingleIdTokenIndexer obj's underlying member method code with example usage: obj.test_crashes_with_empty_feature_value_and_no_default() without return types