The mod D.A.R.T. (1.2.2) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event dart::on_gui_click (ID 1)
Value must be a string in property tree at ROOT.first_signal.name
stack traceback:
    [C]: in function '__newindex'
    __dart__/scripts/ConfigureTurrets.lua:102: in function '?'
    __dart__/scripts/ConfigureTurrets.lua:183: in function 'autoConfigure'
    __dart__/scripts/gui/turrets.lua:550: in function 'handler'
    __dart__/scripts/gui/components.lua:328: in function 'wrapper'
    __flib__/gui.lua:147: in function 'handler'
    __flib__/gui.lua:177: in function 'handler'
    __core__/lualib/event_handler.lua:72: in function <__core__/lualib/event_handler.lua:70>

Occured when clicking on "auto configure" in the FCC.

At a first glance I've no good idea, what's going wrong. Obviously the signal name that was determined isn't valid.

To narrow the problem I need some more info. Do you have a save file that you could share? Or as alternative please set logging level to FINE (in the mod settings) and click again. If the error occurs again (what I am expecting 😉) please share your factorio-current.log. I've opened a github issue where you can post the links or add the files.

I was able to reproduce the bug in the meantime - no further action by you is needed.

V 1.2.3 with a fix is online.

Have fun