Grass seed runtime fix

Fixes grass seeds causing a runtime when putting a stack through the seed extractor with only 1 tile left in the stack.

If the ```use()``` case above this line uses up the last of the tiles it will delete the grass tile before continuing this code. It would then runtime on ```null.name``` since the tile had been deleted.

I'm sure there's a more robust way of fixing it, but eh, this bit of code it only for one specific tile type.