Legacy platform objects' [[DefineOwnProperty]] refers to possibly nonexistent Desc.[[Value]]

[0f-0b]

What is the issue with the Web IDL Standard?

Step 1.3 and 2.2.2.2 of [[DefineOwnProperty]] for legacy platform objects refer to Desc.[[Value]]. It is unclear what should happen if Desc doesn't have a field named [[Value]]:

Reflect.defineProperty(localStorage, "foo", { writable: true });