Just had a multiplayer server crash with this report:

16142.466 Error MainLoop.cpp:1285: Exception at tick 50506124: The mod LTN Combinator Modernized (0.9.8) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event LTN_Combinator_Modernized::on_gui_click (ID 1)
__LTN_Combinator_Modernized__/script/ltn-combinator.lua:317: attempt to perform arithmetic on local 'slot' (a nil value)
stack traceback:
        __LTN_Combinator_Modernized__/script/ltn-combinator.lua:317: in function '_validate_slot'
        __LTN_Combinator_Modernized__/script/ltn-combinator.lua:284: in function 'set_slot_value'
        __LTN_Combinator_Modernized__/script/gui.lua:86: in function 'set_new_output_value'
        __LTN_Combinator_Modernized__/script/gui.lua:299: in function 'handler'
        __flib__/gui.lua:390: in function <__flib__/gui.lua:376>
16142.466 Error ServerMultiplayerManager.cpp:91: MultiplayerManager failed: "The mod LTN Combinator Modernized (0.9.8) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event LTN_Combinator_Modernized::on_gui_click (ID 1)
__LTN_Combinator_Modernized__/script/ltn-combinator.lua:317: attempt to perform arithmetic on local 'slot' (a nil value)
stack traceback:
        __LTN_Combinator_Modernized__/script/ltn-combinator.lua:317: in function '_validate_slot'
        __LTN_Combinator_Modernized__/script/ltn-combinator.lua:284: in function 'set_slot_value'
        __LTN_Combinator_Modernized__/script/gui.lua:86: in function 'set_new_output_value'
        __LTN_Combinator_Modernized__/script/gui.lua:299: in function 'handler'
        __flib__/gui.lua:390: in function <__flib__/gui.lua:376>"

Blargh,

Any chance you have a series of steps to reproduce? Or, a save that it reproduces in? I have been unable to reproduce this specific crash.

I got similar issue with on_gui_confirmed event.
With another map I have been hosting, same crash happened with the other LTN combinator mod (LTN combinator for 1.1).
I was still not able to reproduce this issue reliability.
Note that this issue never happened when I was playing in singleplayer, so I suggest that it is specific to multiplayer.

Crashed when a client try to change the requested item count.

https://imgur.com/cGwaFUf

82896.393 Error MainLoop.cpp:1285: Exception at tick 31944374: The mod LTN Combinator Modernized (0.9.8) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event LTN_Combinator_Modernized::on_gui_confirmed (ID 144)
LTN_Combinator_Modernized/script/ltn-combinator.lua:317: attempt to perform arithmetic on local 'slot' (a nil value)
stack traceback:
LTN_Combinator_Modernized/script/ltn-combinator.lua:317: in function '_validate_slot'
LTN_Combinator_Modernized/script/ltn-combinator.lua:284: in function 'set_slot_value'
LTN_Combinator_Modernized/script/gui.lua:86: in function 'set_new_output_value'
LTN_Combinator_Modernized/script/gui.lua:291: in function 'handler'
flib/gui.lua:390: in function <flib/gui.lua:376>
82896.394 Error ServerMultiplayerManager.cpp:91: MultiplayerManager failed: "The mod LTN Combinator Modernized (0.9.8) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event LTN_Combinator_Modernized::on_gui_confirmed (ID 144)
LTN_Combinator_Modernized/script/ltn-combinator.lua:317: attempt to perform arithmetic on local 'slot' (a nil value)
stack traceback:
LTN_Combinator_Modernized/script/ltn-combinator.lua:317: in function '_validate_slot'
LTN_Combinator_Modernized/script/ltn-combinator.lua:284: in function 'set_slot_value'
LTN_Combinator_Modernized/script/gui.lua:86: in function 'set_new_output_value'
LTN_Combinator_Modernized/script/gui.lua:291: in function 'handler'
flib/gui.lua:390: in function <flib/gui.lua:376>"
82896.394 Info ServerMultiplayerManager.cpp:783: updateTick(31944374) changing state from(InGame) to(Failed)
82896.395 Quitting: multiplayer error.

The mod LTN Combinator Modernized (0.9.8) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event LTN_Combinator_Modernized::on_gui_click (ID 1)
LTN_Combinator_Modernized/script/ltn-combinator.lua:317: attempt to perform arithmetic on local 'slot' (a nil value)
stack traceback:
LTN_Combinator_Modernized/script/ltn-combinator.lua:317: in function '_validate_slot'
LTN_Combinator_Modernized/script/ltn-combinator.lua:284: in function 'set_slot_value'
LTN_Combinator_Modernized/script/gui.lua:86: in function 'set_new_output_value'
LTN_Combinator_Modernized/script/gui.lua:299: in function 'handler'
flib/gui.lua:390: in function <flib/gui.lua:376>

Server shutdown after this error. This is from log. I dont know where has been cklicked

I'm trying to track this down. This actually in the part of the code from the original as confirmed by nans post above. I have yet to reproduce it, and I'm hesitant to make a blind change and just hope that avoids it. However, that may be where we are.

Can any of you provide a save game that this happens with?

I'd obviously like to handle whatever is going on that someone is trying vs. just bail if the value isn't right.

Are you running any other mods that may have some interaction with combinators?

Sorry for the delay in response, it's been a crazy past couple weeks.

The crash happened on my multiplayer server - only one person (not me) was online, and just generically "adjusting LTN requests" when it happened. We haven't seen it since - was a one-time thing, and we use LTN combinators extensively. We've since tried to reproduce a couple different ways, but haven't hit the secret combination yet.

Re: other combinators: We do have the Math Coprocessor mod installed, although none of those are in use. It IS a relatively heavily modded game with ~40 mods or so running.

My server hit this yesterday as well. No repro steps known (when we reloaded the save it didn't re-crash). At the time there were two of us modifying two separate LTN combinators at the same time. There was a console message saying something about the LTN combinator being missing (did it get destroyed?) and then it crashed moments later. We are running Space Exploration with a handful of other mods. Full server log: https://paste.c-net.org/BellmanStandby

My server hit this yesterday as well. No repro steps known (when we reloaded the save it didn't re-crash). At the time there were two of us modifying two separate LTN combinators at the same time. There was a console message saying something about the LTN combinator being missing (did it get destroyed?) and then it crashed moments later. We are running Space Exploration with a handful of other mods. Full server log: https://paste.c-net.org/BellmanStandby

Thanks for the log st4x0r. This is definitely a different crash than the one Blargh2015 reported, but needs to be fixed none-the-less.

@st4rx0r

I think I have the issue you experienced covered. I was not able to reproduce it, but there is a check to make sure it does not crash with the same condition.

Blargh2015 I have been unable to reproduce this crash with a lot of attempts. :( I'll keep working at it, and if you narrow down any conditions to reliably cause it to crash please pass them along.

Yeah, these do appear to be the same after all. Just coming at it from different entry points. Should have been fixed as of 1.0.0