For the nuker, you could have it charge instead of store-so the ghodium is lost when added to the nuker, instead of when it's used.
Labs are trickier. Maybe add a .store.maxMineralType/.store.maxMineralAmount that returns the mineral with the highest count (not including energy, power, etc)? That way it would always work like .mineralType/.mineralAmount does now on labs, plus it would be useful for storage, terminals and creeps too.