Union Type Guard Breaks If Expression Has Property

[Joncom]

TypeScript Version:

1.8.2

Code

interface Foo {
    property: (boolean | { bar: number })
}

var foo: Foo = {
    property: { bar: 123 }
};

var p = foo.property;
if (typeof p === 'object') {
    // This works fine!
    console.log(p.bar); // Prints "123"
}

if (typeof foo.property === 'object') {
    // This line produces the following compilation error:
    // "Property 'bar' does not exist on type 'boolean | { bar: number; }'"
    console.log(foo.property.bar);
}

Expected behavior:

I expected if (typeof foo.property === 'object') { to be a valid type guard.

Actual behavior:

It's not.

[yortus]

Duplicate of #3812?

[DanielRosenwasser]

Thanks for digging that up @yortus!