I was setting up a LTN cleanup station and selected the wrong signal (the anything signal) and got this crash.

The mod LTN Combinator Modernized (1.0.7) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event LTN_Combinator_Modernized::on_gui_elem_changed (ID 68)
Constant combinator: invalid signal in parameters: signal-anything
stack traceback:
[C]: in function 'set_signal'
LTN_Combinator_Modernized/script/ltn-combinator.lua:280: in function 'set_slot'
LTN_Combinator_Modernized/script/gui.lua:374: in function 'handler'
LTN_Combinator_Modernized/lib/gui.lua:390: in function <LTN_Combinator_Modernized/lib/gui.lua:376>

This should be managed now. Those signals will be ignored if selected. Ideally I'd be able to prevent them from being presented as options. An enhancement to the API would be needed.

https://forums.factorio.com/viewtopic.php?p=554711