Hello!

I'm the author of another mod, that inside the script changes one of the settings. This triggers an on_runtime_mod_setting_changed event, which Schall is processing with local function runtime_mod_setting_changed(e) in control.lua around line 98, and that code assumes player_index is set in the event. However, https://lua-api.factorio.com/latest/events.html#on_runtime_mod_setting_changed explicitly says this isn't true in the case of a script changing a setting (which Utilization Monitor Blargh is doing - it's trying to update the mod setting tick box to match what is being toggled).

The problem is in SchallEndgameEvolution, line 98:

local function runtime_mod_setting_changed(e)
  local player = game.players[e.player_index]

One of the people posted something in the discussion for my mod ( https://mods.factorio.com/mod/UtilizationMonitorBlargh/discussion/601a07ccf5bdb41ee3c4791b ) since Factorio shows it at the top and is the hotkey triggering, but the problem seems to be in this mod.

Any chance this can get looked at, and thanks!

Sorry for the waiting. Finally have some time for Factorio modding.

Thanks for reporting.
I was not aware that can be optional, and was not expecting mod settings being changed by script.
Just released 0.17.16 / 0.18.8 / 1.0.2 / 1.1.1, which (hopefully) fixed the problem.

PS1: BTW, your "Show labels" hotkey/option is global, which means it will also affect all other players in a multiplayer game. Right? From a first glance (without actually testing), I thought its nature would be similar to "Alt-mode" hotkey and display, which is per-user basis.

PS2: Some of my earlier-written mods have similar syntax in runtime_mod_setting_changed() calls. Seems I will also need to update/fix them in a few days...

Sorry for the waiting. Finally have some time for Factorio modding.

Thanks for reporting.

No worries!

I was not aware that can be optional, and was not expecting mod settings being changed by script.

A couple people didn't know it either - I had the same issue reported for a couple mods.

PS1: BTW, your "Show labels" hotkey/option is global, which means it will also affect all other players in a multiplayer game. Right? From a first glance (without actually testing), I thought its nature would be similar to "Alt-mode" hotkey and display, which is per-user basis.

It is, and fixing that is on the to-do list (actually at position #1, because it's driving me crazy in the multiplayer games I run :) ), but doing so in a way that doesn't cause multiplayer desyncs is going to be interesting - the first couple takes at it ran into some Fun Issues, heh.

Don't know if you have solved the show labels "per player" problem or not.
I have some experience in this, and never have any MP desync issues. See if it may help you:
If you do the labels via flying-text, you can make use of the render_player property.
If you do it via LuaRendering, then get_players & set_players calls would be useful. I used these in Schall Pickup Tower to mimic radius visualization when player hovers mouse cursor over (like what the game did with turrets and roboports).