Javascript 在不相交的并集类型中找不到属性

以下代码：

/* @flow */

type StepApplicationAction = { type: "STEP_APPLICATION" }
type RewindApplicationAction = { type: "REWIND_APPLICATION" }

type ApplicationAction = StepApplicationAction | RewindApplicationAction

type RequestVinsAction = { type: "REQUEST_VINS" }
type ReceiveVinsAction = { type: "RECEIVE_VINS", vins: Array<string> }

type VehicleAction = RequestVinsAction | ReceiveVinsAction

type Action = ApplicationAction | VehicleAction

function reducer(action: Action) {
  switch (action.type) {
    case "REQUEST_VINS": console.log('HERE')
    case "RECEIVE_VINS":
      console.log(action.vins)
    default:
      return
  }
}

---

不确定本例中我的不相交并集设置有什么问题。

您忘记了从case分支中返回

或
中断
：

/* @flow */

type StepApplicationAction = { type: "STEP_APPLICATION" }
type RewindApplicationAction = { type: "REWIND_APPLICATION" }

type ApplicationAction = StepApplicationAction | RewindApplicationAction

type RequestVinsAction = { type: "REQUEST_VINS" }
type ReceiveVinsAction = { type: "RECEIVE_VINS", vins: Array<string> }

type VehicleAction = RequestVinsAction | ReceiveVinsAction

type Action = ApplicationAction | VehicleAction

function reducer(action: Action) {
  switch (action.type) {
    case "REQUEST_VINS": console.log('HERE'); return;
//                                            ^^^^^^^
    case "RECEIVE_VINS":
      console.log(action.vins); return;
    default:
      return;
  }
}

/*@flow*/
类型StepApplicationAction={type:“STEP_应用程序”}
类型RewindApplicationAction={type:“REWIND_应用程序”}
类型ApplicationAction=步骤ApplicationAction |倒带ApplicationAction
类型RequestVinsAction={type:“REQUEST_VINS”}
type ReceiveVinsAction={type:“RECEIVE_VINS”，VINS:Array}
类型VehicleAction=RequestVinsAction | ReceiveVinsAction
类型动作=应用动作|车辆动作
功能减速机（动作：动作）{
开关（动作类型）{
案例“REQUEST_VINS”：console.log（'HERE'）；return；
//                                            ^^^^^^^
“接收”案例：
console.log（action.vins）；返回；
违约：
返回；
}
}

您忘记了从案例分支中返回
或
中断
：

/* @flow */

type StepApplicationAction = { type: "STEP_APPLICATION" }
type RewindApplicationAction = { type: "REWIND_APPLICATION" }

type ApplicationAction = StepApplicationAction | RewindApplicationAction

type RequestVinsAction = { type: "REQUEST_VINS" }
type ReceiveVinsAction = { type: "RECEIVE_VINS", vins: Array<string> }

type VehicleAction = RequestVinsAction | ReceiveVinsAction

type Action = ApplicationAction | VehicleAction

function reducer(action: Action) {
  switch (action.type) {
    case "REQUEST_VINS": console.log('HERE'); return;
//                                            ^^^^^^^
    case "RECEIVE_VINS":
      console.log(action.vins); return;
    default:
      return;
  }
}

/*@flow*/
类型StepApplicationAction={type:“STEP_应用程序”}
类型RewindApplicationAction={type:“REWIND_应用程序”}
类型ApplicationAction=步骤ApplicationAction |倒带ApplicationAction
类型RequestVinsAction={type:“REQUEST_VINS”}
type ReceiveVinsAction={type:“RECEIVE_VINS”，VINS:Array}
类型VehicleAction=RequestVinsAction | ReceiveVinsAction
类型动作=应用动作|车辆动作
功能减速机（动作：动作）{
开关（动作类型）{
案例“REQUEST_VINS”：console.log（'HERE'）；return；
//                                            ^^^^^^^
“接收”案例：
console.log（action.vins）；返回；
违约：
返回；
}
}