Got a crash when my brother joined my game via steam, the second he finished loading.

723.862 Error MainLoop.cpp:1429: Exception at tick 32750063: The mod Factory Palette (0.3.1) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event factory-palette::on_gui_location_changed (ID 158)
factory-palette/scripts/gui/search.lua:91: attempt to index local 'gui_data' (a nil value)
stack traceback:
factory-palette/scripts/gui/search.lua:91: in function 'fn'
factory-palette/handlers.lua:20: in function <factory-palette/handlers.lua:16>
factory-palette/scripts/gui/search.lua:582: in function 'wrapper'
flib/gui.lua:147: in function 'handler'
flib/gui.lua:177: in function 'handler'
core/lualib/event_handler.lua:47: in function <core/lualib/event_handler.lua:45>

I wasn't able to test this, but I made a change that should at least change how you crash, if you still do, on 0.4.0. Let me know if that makes it better. I'll try to test multiplayer soon though.

I think 0.4.2 addresses this now.