Why is accidentally drinking a canister of sludge even an option?

[Mossflower]

If you have one empty canister and you click the action bar to fill it, it'll replace itself with a full canister of sludge. If, god forbid, you click it again, thinking you have more empties... You drink sludge... which poisons you. I'm fine with it being a thing you can do for some random reason, I guess. But it can be kind of annoying while trying to fill the canisters up...