Overload resolution selects most narrow overload when `any` is involved

TypeScript Version: 4.0.0-dev.20200730

Search Terms: any overload

Code

declare class Endpoint {}

declare function getEndpoint(index: number): Endpoint | undefined;
declare function getEndpoint(index: 0): Endpoint;

declare const i1: number | undefined;
const e1 = getEndpoint(i1 ?? 0); // Endpoint | undefined, as expected

declare const i2: any;
const e2 = getEndpoint(i2); // Endpoint, expected Endpoint | undefined

Expected behavior:
The type of e2 should include undefined, since we cannot know that the most narrow overload always matches.

Actual behavior:
It does not.

I understand that it is not always possible to select a sound overload, especially when the possible argument types are not strictly subsets of each other. However choosing the most narrow overload does not seem correct.
Take this extension of the repro for example:

declare class Endpoint {}

declare function getEndpoint(index: number): Endpoint | undefined;
declare function getEndpoint(index: 1 | 2): "FOOBAR";
declare function getEndpoint(index: 0): Endpoint;

declare const i3: any;
const e3 = getEndpoint(i3);

Here, e3 is inferred as Endpoint. When I change the argument in the 2nd overload to 1 instead of 1 | 2, e3 suddenly has type "FOOBAR". I would argue that it is not possible to narrow to any overload here, since i3 could be any number (or even any other type).
Therefore I believe that the most sound result would be the union of all return types, that is Endpoint | undefined | "FOOBAR".

Playground Link: Playground Link

Related Issues: none found that seems to match this one

TypeScript playground での再現から始め、引数の型が any である呼び出しのオーバーロード解決を追跡してください。e2 と e3 の推論された型を、期待される戻り値型のユニオンと比較してください。報告されたケースで最も狭いオーバーロードだけが選択されなくなり、関連するコンパイラテストでこの動作がカバーされれば完了です。