Ran across this bug when I was placing down one of the LTN combinators:

The mod LTN Combinator Modernized (2.2.3) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event LTN_Combinator_Modernized::on_built_entity (ID 6)
value for required parameter 2 (filter) is missing
stack traceback:
[C]: in function 'set_slot'
LTN_Combinator_Modernized/script/ltn_combinator.lua:282: in function 'set_ltn_signal_by_control'
LTN_Combinator_Modernized/script/ltn_combinator.lua:1704: in function 'create_storage_data_from_combinator'
LTN_Combinator_Modernized/script/ltn_combinator.lua:1762: in function 'handler'
core/lualib/event_handler.lua:47: in function <core/lualib/event_handler.lua:45>

I don't know what the problem is as I am not a coder but it might have something to do with a lua library