TypeError Cannot serialize non-str key None

[JGRGIT]

When running adsbxcot -c config.ini the script throws exception below.

--start config.ini--
[adsbxcot]
#COT_URL = tcp://url:8087
#FEED_URL = https://api.airplanes.live/v2/point/xx.xxx/1yy.yyy/200
#FEED_URL = https://api.airplanes.live/v2/mil
FEED_URL = https://opendata.adsb.fi/api/v2/lat/xx.xxx/lon/yy.yyy/dist/200
POLL_INTERVAL = 5

PYTAK_TLS_DONT_VERIFY = 1
PYTAK_TLS_DONT_CHECK_HOSTNAME = 1

PREF_PACKAGE = /home/pytak/Downloads/xyz.zip
--end config.ini--

I have tried COT_URL to url:8087 without security, # in the config above.
Different adsbx and with different parameters in the url, # in the config above.

2024-05-21 19:13:44,766 pytak INFO - Using COT_URL='ssl://url:8089'
2024-05-21 19:13:44,768 pytak INFO - Run: CLITool
2024-05-21 19:13:44,769 pytak INFO - Run: TXWorker
2024-05-21 19:13:44,769 pytak INFO - Running <class 'adsbxcot.classes.ADSBXWorker'>
2024-05-21 19:13:44,769 pytak INFO - <class 'adsbxcot.classes.ADSBXWorker'> polling every 5s: https://opendata.adsb.fi/api/v2/lat/xx.xxxxxx/lon/yy.yyyyyy/dist/200
2024-05-21 19:13:44,799 pytak INFO - Run: RXWorker
2024-05-21 19:13:44,857 pytak INFO - Complete: <Task finished name='Task-3' coro=<ADSBXWorker.run() done, defined at /home/pytak/.local/lib/python3.12/site-packages/adsbxcot/classes.py:133> exception=TypeError('Cannot serialize non-str key None')>
ERROR:asyncio:Task exception was never retrieved
future: <Task finished name='Task-3' coro=<ADSBXWorker.run() done, defined at /home/pytak/.local/lib/python3.12/site-packages/adsbxcot/classes.py:133> exception=TypeError('Cannot serialize non-str key None')>

Any help is greatly appreciated.