This happened while placing a Beacon with modded quality (if it matters, it was on a Space Platform).

Error while running event AutoBestQuality:on_space_platform_built_entity (ID 80)
Index out of inventory bounds.
stack traceback:
[C]: in function 'index'
__AutoBestQuality/ghost_processor.lua:606: in function 'reapply_settings'
AutoBestQuality/upgrade_handler.lua:283: in function 'handle_entity_built'
AutoBestQuality/event_handlers.lua:134: in function <AutoBestQuality/event_handlers.lua:91>

Thanks for your report, i think this was because the amount of module slots changed with the quality level. This should now be fixed.