Key error during preprocesssing about hgraph2graph HOT 6 OPEN

rdkit                     2019.03.4.0      py37hc20afe1_1
python                    3.7.6                h0371630_2
pytorch                   1.12.0          py3.7_cuda11.6_cudnn8.3.2_0
numpy                     1.21.5           py37h6c91a56_3

multiprocessing.pool.RemoteTraceback:
"""
Traceback (most recent call last):
  File "/home/marcase/.conda/envs/hgraph-rdkit/lib/python3.7/multiprocessing/pool.py", line 121, in worker
    result = (True, func(*args, **kwds))
  File "/home/marcase/.conda/envs/hgraph-rdkit/lib/python3.7/multiprocessing/pool.py", line 44, in mapstar
    return list(map(*args))
  File "preprocess.py", line 19, in tensorize
    x = MolGraph.tensorize(mol_batch, vocab, common_atom_vocab)
  File "/home/marcase/hgraph2graph/hgraph/mol_graph.py", line 153, in tensorize
    tree_tensors, tree_batchG = MolGraph.tensorize_graph([x.mol_tree for x in mol_batch], vocab)
  File "/home/marcase/hgraph2graph/hgraph/mol_graph.py", line 194, in tensorize_graph
    fnode[v] = vocab[attr]
  File "/home/marcase/hgraph2graph/hgraph/vocab.py", line 43, in __getitem__
    return self.hmap[x[0]], self.vmap[x]
KeyError: 'C1=CNN=C1'
"""
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
  File "preprocess.py", line 106, in <module>
    all_data = pool.map(func, batches)
  File "/home/marcase/.conda/envs/hgraph-rdkit/lib/python3.7/multiprocessing/pool.py", line 268, in map
    return self._map_async(func, iterable, mapstar, chunksize).get()
  File "/home/marcase/.conda/envs/hgraph-rdkit/lib/python3.7/multiprocessing/pool.py", line 657, in get
    raise self._value
KeyError: 'C1=CNN=C1'