Anonymous function breaks discriminated intersection type narrowing

[frederikschubert]

TypeScript Version:
2.0.0
Code

class ControllerSelectAction implements Action {
    type: "CONTROLLER_SELECT";
    payload: Controller;
}

export class ControllerRefreshAction implements Action {
    type: "CONTROLLER_REFRESH";
}

type ControllerAction = ControllerSelectAction | ControllerRefreshAction;

const controllerReducer(state: any, action: ControllerAction) {
    switch(action.type) {
        case "CONTROLLER_REFRESH":
        return state.set("refresh", true);

        case "CONTROLLER_SELECT":
        return state.update("selected", (controller) => controller.id === action.payload.id ? controller : action.payload));
}

Expected behavior:
action should be narrowed to the ControllerSelectAction class in the anonymous function in the CONTROLLER_SELECT case, so that no error is thrown when accessing action.payload.id.

Actual behavior:
The following error is thrown:

Property 'payload' does not exist on type 'ControllerSelectAction | ControllerRefreshAction

[sandersn]

This is a known breaking change in 2.0: https://github.com/Microsoft/TypeScript/wiki/Breaking-Changes. See also #7662.

[frederikschubert]

I didn't know that document yet. Sorry for the duplicate and thanks for your quick answer! :)