Wrong report of TS2525

[n9]

TypeScript Version: 3.0.1 and also current @next 3.1.0-dev.20180821

Search Terms: TS2525

Code

interface Foo {
    b?: string
}

function bar1(arg?: Foo): void {
    const { b } = arg || {}
}

function bar2(arg?: Foo): void {
    const da = arg || {}
    const { b } = da
}

Expected behavior:
No error.

Actual behavior:
bar1 shows error: TS2525: Initializer provides no value for this binding element and the binding element has no default value.

Playground Link: https://www.typescriptlang.org/play/#src=interface%20Foo%20%7B%0D%0A%20%20%20%20b%3F%3A%20string%0D%0A%7D%0D%0A%0D%0Afunction%20bar1(arg%3F%3A%20Foo)%3A%20void%20%7B%0D%0A%20%20%20%20const%20%7B%20b%20%7D%20%3D%20arg%20%7C%7C%20%7B%7D%0D%0A%7D%0D%0A%0D%0Afunction%20bar2(arg%3F%3A%20Foo)%3A%20void%20%7B%0D%0A%20%20%20%20const%20da%20%3D%20arg%20%7C%7C%20%7B%7D%0D%0A%20%20%20%20const%20%7B%20b%20%7D%20%3D%20da%0D%0A%7D

Related Issues: no (only #21634)

[AlCalzone]

Duplicate of #26235?

[n9]

@AlCalzone Yes, seems to.