.off() is not working properly for listeners added by .once()

[aishikaty]

This doesn't seem to work as expected:

const emitter = dush()
const hello = () => console.log("You shouldn't see this.")
emitter.once('test', hello)
emitter.off('test', hello)
emitter.emit('test')

[tunnckoCore]

Interesting. More and more bugs with that implemantation of .off. I think #7 is related to it too.

[tunnckoCore]

Actually, @aishikaty, it not make much sense to off something that is added by once because it is offed by default, internally. That's the whole point of once.\

Nevermind, i got your logic, and it I fixed that, so now it is working. I'm going to push fixes in a bit.