No suggestion diagnostic for unchecked JS files in method from class

[DanielRosenwasser]

class Person {
    getFavoriteColor() {

    }
}

const person = new Person();
person.getFavoriteColour();

Expected

A suggestion diagnostic:

Property 'getFavoriteColour' may not exist on type 'Person'. Did you mean 'getFavoriteColor'?

Actual

No suggestion diagnostic.

In contrast, see this example:

const person = {
    getFavoriteColor() {

    }
}

person.getFavoriteColour();

[DanielRosenwasser]

Ugh, from #44271

The error is suppressed for property accesses on a class because the compiler doesn't understand JS constructor functions well enough. In particular, it doesn't understand any inheritance patterns.

[sandersn]

I think that rule could be improved to allow suggestions from class types that are known to come from a class declaration or expression which don't have an extends clause. It's constructor functions where I observed the bad suggestions, and it's possible that completions from a base class might also be bad.

That rule is even harder to explain though.