instanceof narrows to never on else branch for Function extending class

[dragomirtitian]

Bug Report

🔎 Search Terms

insatnceof extends function

🕗 Version & Regression Information

• This changed between versions 5.0.0-dev.20221129 and 5.0.0-dev.20221130

⏯ Playground Link

Playground link with relevant code

💻 Code

class PersonMixin extends Function {
    public [Symbol.hasInstance](o: any) {
        return typeof o === "object" && o !== null && o instanceof Person;
    }    
}
const cls = new PersonMixin();

class Person {
    work(): void { console.log("work") }
    sayHi(): void { console.log("Hi") }
}
class Car {
    sayHi(): void { console.log("Wof Wof") }
}

function test(o: Person | Car) {
    if (o instanceof cls) {
        console.log("Is Person");
        (o as Person).work()
    }
    else {
        console.log("Is Car")
        o.sayHi(); //o is never in 5.0. Was Person | Car in 4.9
    }
}
test(new Person)
test(new Car)

🙁 Actual behavior

o is never on the else branch. causing an error

🙂 Expected behavior

o is Person | Car as it was in 4.9 since the type guard doesn't really say a lot about the type of o in the type system.

[ahejlsberg]

This is an effect of #51631. It fixed isTypeDerivedFrom to correctly handle {}, but turns out narrowTypeByInstanceof was relying on the old inconsistent behavior. That needs fixing too.