A bug on overriding nested property of a non-configurable property

[theseanl]

Steps to reproduce:

var base = {};

Object.defineProperty(base, 'a', {
    value: {},
    writable: true,
    enumerable: true,
    configurable: false
});

AG_defineProperty('a.b', { value: 1 }, base);
AG_defineProperty('a.c.d', { value: 2 }, base);

base.a.c = {};

console.log(base.a.c.d);

Expected:

2

Actual:

undefined