Tenho um dataframe do Pandas e quero calcular os bigrams com o seguinte código:

from nltk import bigrams
df['tweet_bigrams'] = df['tweet_tokenized'].apply(lambda x: list(bigrams(x)))

Ele estava funcionando bem em Jupyter. No entanto, quando tentei executá-lo no terminal Linux, continuo recebendo o seguinte erro:

Traceback (most recent call last):
   File "/usr/licensed/anaconda3/5.3.1/lib/python3.7/site-packages/nltk/util.py", line 468, in ngrams
history.append(next(sequence))
StopIteration

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
   File "url_tweet_feature_extraction.py", line 143, in <module>
    df['tweet_bigrams'] = df['tweet_tokenized'].apply(lambda x: list(bigrams(x)))
  File "/usr/licensed/anaconda3/5.3.1/lib/python3.7/site-packages/pandas/core/series.py", line 3194, in apply
mapped = lib.map_infer(values, f, convert=convert_dtype)
  File "pandas/_libs/src/inference.pyx", line 1472, in pandas._libs.lib.map_infer
  File "url_tweet_feature_extraction.py", line 143, in <lambda>
df['tweet_bigrams'] = df['tweet_tokenized'].apply(lambda x: list(bigrams(x)))
  File "/usr/licensed/anaconda3/5.3.1/lib/python3.7/site-packages/nltk/util.py", line 491, in bigrams
for item in ngrams(sequence, 2, **kwargs):
RuntimeError: generator raised StopIteration

Alguma idéia de como resolver isso?