Got an error when use "now - transmission_date_done"

[ProteinPig]

I have a task to clean seeds from transmission when finished 2days. It worwed very well, but today it didn't worked. I looked into the log and I found the error.
Is there anything wrong with this config?

2021-01-29 04:00:27 ERROR if clean_temp_seeds Error occurred while evaluating statement now - transmission_date_done >= timedelta(days=2) and 'temp' in transmission_downloadDir. (unsupported operand type(s) for -: 'datetime.datetime' and 'NoneType')

   clean_temp_seeds:
    priority: 1002
    <<: *from_transmission
    if:
      - transmission_ratio >= 3.0 and 'temp' in transmission_downloadDir: accept
      - now - transmission_date_done >= timedelta(days=2) and 'temp' in transmission_downloadDir: accept
    <<: *clean_transmission

Version Info
Flexget: 3.1.98
API: 1.8.0

[ProteinPig]

OK, found it.
It's because the seed is unfinished.
So I should reject it if transmission_progress != 100.0