(arr || []).filter... Is something I do when I'm not sure if the array is null or not. Looks shitty but works fine. (Now if arr is not falsy and not an array either, this blows up. But I don't know what lodash does then too)

To be honest, I'd rather check / handle nulls rather than to rely on an external library semantics. They might also change it tomorrow and upgrading would be a pain.