object is possibly undefined even though check is done #34535

TypeScript Version: 3.6.3

Search Terms: object is possibly undefined

Code

const foo = (bar: { baz?: { name: string } }) => {
    const isBarBazDefined = !!bar.baz;
    if(isBarBazDefined) console.log(bar.baz.name);
}

Expected behavior:
Typescript should not give an 'object is possibly undefined' error.

Actual behavior:
Typescript does give an 'object is possibly undefined' error.

Playground Link:
http://www.typescriptlang.org/play/?ssl=4&ssc=2&pln=1&pc=1#code/MYewdgzgLgBAZiEMC8MAUAjAhgJwFwwDeM2AXgPwHFhYC2ApgdDgJZgDmMAvtwJQoA+IgCgYYmKEiwWEAEK55pACL04begBMUMAIQ7sOAHRkA3KPEs4aGfJyKVasJv6SIIADb1D7kO0y5jLFJDGgZeMy4gA

Related Issues:
Couldn't find any.

I realise this is very simple case, but I haven't been able to find an existing issue or FAQ entry on the subject...