I've been playing with Nullius. I noticed that an inserter icon appeared in the upper right corner of the screen at some point. I used the GUI Manager to hide this icon successfully.
However, when I loaded the save game for the second time, I noticed that the icon reappeared.
So, I tried using the GUI Manager again and found that the option to hide the icon was unchecked. When I clicked to check it, the game crashed.
I hope you can fix this issue. Thanks in advance.

Error while running event guiManager::on_gui_checked_state_changed (ID 3)
LuaGuiElement API call when LuaGuiElement was invalid.
stack traceback:
[C]: in function 'newindex'
__guiManager/control.lua:305: in function <guiManager/control.lua:296>

Hey, thanks for the report. I will try to get this mod updated for you. It has been several years since I've really worked on any factorio mods, but from your message it seems pretty straightforward what needs to be addressed.

Are you able to try with the latest version? I added a check to make sure the target GUI was valid. I feel like there may be some side effects, but I don't have the time to investigate.

If anyone else would like to contribute to further development of the mod, let me know :)

Now I can hide this icon without any crashes. Thanks.