Default is working wrong for nested null value

[vladshcherbin]

import delve from 'dlv'

let obj = {
  a: {
    c: 1,
    d: undefined,
    e: null
  }
}

console.log(delve(obj, 'a.c', 'default')) // 1
console.log(delve(obj, 'a.c.f', 'default')) // default

console.log(delve(obj, 'a.d', 'default')) // default
console.log(delve(obj, 'a.d.f', 'default')) // default

console.log(delve(obj, 'a.e', 'default')) // null
console.log(delve(obj, 'a.e.f', 'default')) // null <- bug

The last one is nested key over null value, it doesn't exist but returns null instead of default value.