Clicking on or maybe trying to close the gui of a T1 shortwave radio (or maybe its selection channel) inside of a sandbox from the Blueprint Sandboxes mod caused this error:
The mod RadioNetwork_FIX (1.0.3) caused a non-recoverable error.
Please report this error to the mod author.
Error while running event RadioNetwork_FIX::on_gui_closed (ID 89)
__RadioNetwork_FIX__/control.lua:452: attempt to index local 'radio' (a nil value)
stack traceback:
__RadioNetwork_FIX__/control.lua:452: in function <__RadioNetwork_FIX__/control.lua:445>
Unfortunately I haven't been able to reproduce it, so don't know exactly what conditions cause it. All I can say is that I had selected some channels on some of the radios, but I'm not sure if the one that caused the error had a channel selected.