we play on 0.16.36
I was opening a previously made blueprint to change the icons - went to the gui in attach notes and right clicked quickly on all icons - after clicking on the last one, the icons reappeared and the multiplayer server crashed:
2342.765 Error MainLoop.cpp:1029: Exception at tick 26890196: Error while running event attach-notes::on_gui_elem_changed (ID 67)
LuaGuiElement API call when LuaGuiElement was invalid.
stack traceback: attach-notes/scripts/blueprint-notes/gui-templates.lua:307: in function 'getTarget' attach-notes/scripts/blueprint-notes/gui-templates.lua:248: in function 'onChanged' attach-notes/scripts/blueprint-notes/gui-templates.lua:29: in function '?' attach-notes/scripts/gui-tools.lua:187: in function 'handleGuiEvent' attach-notes/scripts/gui-tools.lua:194: in function 'func' attach-notes/control.lua:98: in function <attach-notes/control.lua:97
hope this gives you enough information - love the mod!
edit: It crashed a second time, when I left clicked on first icon to change that to another. exactly the same bug log.