While that is a nice ‘Safety’ feature, can you and that guy test it, with other blocks and small amount, to see if that was a bug that it was still in trade, or if it actually saved it and remembered it?
Even bring in a third guy, ‘crash’ with the first one, then trade with the second one and see if the item is there too. Cause if it’s in any trade, all the better.
But if it’s only in a specific trade to a specific player, I can see people abusing that by waiting for you to trade something expencive or big, then ‘crash’ on purpose and never trading with you again after that, so you effectively lose those items.
If it works, and it’s a safety feature you can even add it to: