Elm http请求返回成功请求的NetworkError

import Http
import Json.Decode exposing (Decoder, field, string)
import Result exposing (Result(..))

type alias User =
    { name : String
    , age : Int
    }

type Msg
    = FetchUser
    | UserFetched (Result Http.Error User)

fetchUser : Cmd Msg
fetchUser =
    Http.get
        { url = "https://api.example.com/user"
        , expect = Http.expectJson UserFetched userDecoder
        }

userDecoder : Decoder User
userDecoder =
    Json.Decode.map2 User
        (field "name" string)
        (field "age" int)

update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    case msg of
        FetchUser ->
            ( model, fetchUser )

        UserFetched (Ok user) ->
            -- 处理成功返回的用户数据
            ( { model | user = Just user }, Cmd.none )

        UserFetched (Err error) ->
            case error of
                Http.NetworkError ->
                    -- 处理NetworkError
                    ( { model | errorMessage = Just "网络错误" }, Cmd.none )

                Http.BadStatus _ ->
                    -- 处理其他错误类型
                    ( { model | errorMessage = Just "其他错误" }, Cmd.none )

                _ ->
                    -- 处理其他错误类型
                    ( { model | errorMessage = Just "未知错误" }, Cmd.none )