Python3 error?

[scriptzteam]

python3 CowrieAnalyzer.py

/usr/lib/python3/dist-packages/matplotlib/font_manager.py:273: UserWarning: Matplotlib is building the font cache using fc-list. This may take a moment.
  warnings.warn('Matplotlib is building the font cache using fc-list. This may take a moment.')
/usr/lib/python3/dist-packages/matplotlib/font_manager.py:273: UserWarning: Matplotlib is building the font cache using fc-list. This may take a moment.
  warnings.warn('Matplotlib is building the font cache using fc-list. This may take a moment.')
Traceback (most recent call last):
  File "CowrieAnalyzer.py", line 120, in <module>
    CowrieAnalyzer().run()
  File "CowrieAnalyzer.py", line 63, in run
    if 'SSH' in event['system']:
KeyError: 'system'