Typescript 广义泛型类型不加载抽象类型上下文

请考虑以下代码:

type ResourceData = {
  user: { id: number; name: string; email: string }
  product: { id: number; name: string; price: number }
  order: { id: number; userId: number; productId: number; quantity: number }
}

type ResourceAction<T extends keyof ResourceData> = {
  type: T
  payload: ResourceData[T]
}

function fetchActionData<T extends keyof ResourceData>(
  action: ResourceAction<T>,
) {
  const actionPayload = action.payload as ResourceData[T] // <---- not working well, it's look only for id.

  switch (action.type) {
    case "product":
      const product = action.payload as ResourceData["product"]
      return `product is ${product.name}`
    case "order":
      const order = action.payload as ResourceData["order"]
      return `order is ${order.productId}`
    case "user":
      const user = action.payload as ResourceData["user"]
      return `name is ${user.name}`
    default:
      return
  }
}

const userAction: ResourceAction<"user"> = {
  type: "user",
  payload: { id: 1, name: "Alice", email: "alice@example.com" },
}

const productAction: ResourceAction<"product"> = {
  type: "product",
  payload: { id: 101, name: "Widget", price: 19.99 },
}

const orderAction: ResourceAction<"order"> = {
  type: "order",
  payload: { id: 1001, userId: 1, productId: 101, quantity: 3 },
}

console.log(fetchActionData(userAction))
console.log(fetchActionData(productAction))
console.log(fetchActionData(orderAction))

当我try 删除此代码时:

const product = action.payload as ResourceData['product'];

...并在Switch Case上创建新常量:

const actionPayload = action.payload as ResourceData[T]

使用后:

    case "user":
      return `name is ${actionPayload.name}`

TypeScrip引发以下错误:

Property 'name' does not exist on type '{ id: number; name: string; email: string; } | { id: number; name: string; price: number; } | { id: number; userId: number; productId: number; quantity: number; }'.

而当判断context时，它只包含id个字段. 为什么会发生这种情况，我如何才能修复它？