If a recipe whose getCraftingResult return EMPTY while matches return true, crafting this recipe would cause the game stucks. I know this is incorrect but this won't cause trouble without FastWorkBench. Adding one more check would improve compatibility and robustness.

That's not supported behavior, the only thing I might do is fire a proper exception.

That's not supported behavior, the only thing I might do is fire a proper exception.

Maybe do another check, log a warning and break that loop would be more friendly.