I getting following error during game. My setup is simple - I attached block to radar to show enemies on GUI, but I getting this error at some point. ~(presumably when enemy enters radar range, and radar emit its signal)~

UPD: Steps to reproduce - attach block to radar, and make sure enemy is in range of radar.

Stacktrace:

Error while running event visual-signals::on_tick (ID 0)
__visual-signals__/signal_gui.lua:40: attempt to index local 'prototype' (a nil value)
stack traceback:
    __visual-signals__/signal_gui.lua:40: in function 'UpdateSingleSignal'
    __visual-signals__/signal_gui.lua:61: in function 'addSignalsToGui'
    __visual-signals__/signal_gui.lua:76: in function 'UpdateSignalGuiPanel'
    __visual-signals__/control.lua:185: in function 'updateUICombinator'
    __visual-signals__/control.lua:196: in function <__visual-signals__/control.lua:193>

still same error...

While I think I know how to fix this, I haven't been able to reproduce this, how do you manage to get entities to become signals exactly?

Also, reason it takes time is because I'm not playing any Factorio these days, and therefore also not doing any mod development.

I think this mod make this happen: https://mods.factorio.com/mod/asteroid-enemy-radar-detection