std::out_of_range in StreamReader

Got an

[Wed Feb 16 03:16:27 2022] [!!!] Slipping data to fit time!
[Wed Feb 16 03:16:27 2022] [!!!] Slipping data to fit time!
[Wed Feb 16 03:16:29 2022] [!!!] Slipping data to fit time!
[Wed Feb 16 03:16:30 2022] [!!!] Slipping data to fit time!
[Wed Feb 16 03:16:31 2022] [!!!] Slipping data to fit time!
terminate called after throwing an instance of 'std::out_of_range'
  what():  map::at

after running StreamReader a long time...