JobResult issue with Error about fstoolkit.errorhandling HOT 3 CLOSED

let dummy a =
    match a with
    | 5 -> Ok true
    | _ -> Error "Not 5"

let dummyList a =
    match a with
    | 5 -> Ok true
    | _ -> Error ["Not 5"]

let loginEx (userDBService : IUserDBService) (fileService : IFileService) username password =
    jobResult {
        let! a = dummy 5 |> mapError List.singleton
        let! b = dummyList 5 
    }

type DummyErrors =
| Not5
let dummy a =
    match a with
    | 5 -> Ok true
    | _ -> Error DummyErrors.Not5

type DummyListErrors =
| Not5
| Never5
let dummyList a =
    match a with
    | 5 -> Ok true
    | _ -> Error [DummyListErrors.Not5]

type LoginErrors =
|  DummyErrors of DummyErrors
| DummyListErrors of DummyListErrors list

let loginEx (userDBService : IUserDBService) (fileService : IFileService) username password =
    jobResult {
        let! a = dummy 5 |> mapError LoginErrors.DummyErrors
        let! b = dummyList 5  |> mapError LoginErrors.DummyListErrors
    }