The exception is an AIFP issue I'll attempt to fix today. At what point did you experience it? I suspect it is due to the unusual steps you've taken and path sequence mentioned below. Nonetheless, now that it's happened, it needs to be fixed.
As for the path to textures, are you sure you're right about moving aircraft? That seems like an unusual requirement. How is the path to the aircraft to be found? If this is documented somewhere in the MSFS SDK, please point me to it. Aircraft paths in other parts of MSFS are Simobjects\Airplane\title\Texture, model etc - quite unlike your modified path. In any case, someone else will have to advise you there.