fail to syllabify 'engraved'

[alephpi]

Hello, thank you for the useful tools. However, when I run

python3 syllabify engraved

An error occurs

Traceback (most recent call last):
  File "syllable3.py", line 366, in <module>
    for syll in syllable:
  File "syllable3.py", line 169, in factory
    syllable_list = functools.reduce(syllable_fact, cluster_list, [Syllable()])
  File "syllable3.py", line 65, in syllable_fact
    syllable = syllable_list.pop()
AttributeError: 'NoneType' object has no attribute 'pop'

Could you verify and debug this problem?

[alephpi]

Another finding: engraved can be syllabified by the python2 version. Maybe something to do with your adaptation.