Getting this when there are multiple people using the GUI on a server and one of the cores does not have any fluids
```
55258.950 Error MainLoop.cpp:1283: Exception at tick 13866089: The mod 248k Mod (0.9.3) caused a non-recoverable error.
Please report this error to the mod author.
Error while running event 248k::on_gui_click (ID 1)
LuaGuiElement API call when LuaGuiElement was invalid.
stack traceback:
[C]: in function 'index'
__248k/scripts/gui.lua:450: in function 'on_change'
248k/control.lua:119: in function <248k/control.lua:118>
55258.950 Error ServerMultiplayerManager.cpp:91: MultiplayerManager failed: "The mod 248k Mod (0.9.3) caused a non-recoverable error.
Please report this error to the mod author.
Error while running event 248k::on_gui_click (ID 1)
LuaGuiElement API call when LuaGuiElement was invalid.
stack traceback:
[C]: in function 'index'
__248k/scripts/gui.lua:450: in function 'on_change'
248k/control.lua:119: in function <248k/control.lua:118>"
```
ill look into that - might be a easy fix. Can i give you a snapshot version to test if the bug was fixed?