downloader.py - '<' not supported between instances of 'NoneType' and 'dateime.datetime'

[ApexLead]

I exported 1 group with around 1M messages to test if the script runs smoothly for me, but when it got to 97% it crushed with another error:
File "/usr/local/lib/python3.6/dist-packages/telegram_export/downloader.py", line 507, in start req.offset_date = min(m.date for m in history.messages)
TypeError: '<' not supported between instances of 'NoneType' and 'dateime.datetime'

[ApexLead]