I'm working my way through this same error as well, been digging for information. Is your refined storage system exporting to a mekanism factory? I haven't been able to test it, but diesel's response makes me wonder about mine exporting into a enrichment factory, dont remember if it is basic or advanced (leaning toward advanced).
Edit: got to test this, removed my RS controller, still crashed. Going to remove all factory's and replace them as the next test.
Edit 2:It is a problem with the factory's, in my case it seems to be between them and my ender io conduit setup, but removing them did stop my game from crashing. Not 100% sure what exactly caused it though.