unable to access conditional generic's expected property

[snow badger]

Elemelon#6133

Playground Link

Preview:```ts
import React from "react"

type Button = {_type: "button"; button: string}
type Icon = {_type: "icon"; icon: string}

export type ButtonOrIcon = Button | Icon

export type Conditional1<P extends ButtonOrIcon> =
P["_type"] extends "button"
? Button
: P["_type"] extends "icon"
? Icon
: never
...```

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[blissful anchor]

i think it's because a condition like P["_type"] extends "button" ? doesn't trigger disributivity, while P extends {_type:"button"} ? does

see https://www.typescriptlang.org/docs/handbook/2/conditional-types.html#distributive-conditional-types if you don't know what that means