

I don’t think you need to directly edit the script if that’s what you mean. You want to edit the values in the plug-in menu so it’s not out of bounds. Those get passed to the script, which then executes.
You probably need the direct error instead of this raised exception. Start Gimp from a terminal, trigger the error, and see if the terminal error is showing exactly what the script’s error is.
Well poking around, it seems that specific plugin was only meant for Gimp 2.10, and you must be on 3.0+ by now, so I would consider it unusable.