Error handler builder usage

ExampleService.fs

open EasyNetQ

type IService =
    abstract member Start : unit -> unit

type Service (log : ILog, bus : IBus, indexer : IIndex, audit : IErrorHandlerBuilder) =
    member this.Start () =
        bus.Subscribe<PasngrEmail>("Archive", 
            fun (email : PasngrEmail) -> 
                audit {
                    log.Debug <| sprintf "Email message %s from recipient %d received for archiving." email.MailUid email.Id
                    let! mail = Some email
                    return indexer.Add email } |> ignore)
        bus.Respond<RetrieveEmailContentRequest, RetrieveEmailContentResponse>(fun request -> 
            let mimeData = audit {
                    log.Debug <| sprintf "Request for content of email %A received." request
                    let! req = Some request
                    return indexer.Retrieve(req)
                }
            match mimeData with
            | Some content -> { Content = content }
            | None -> { Content = "No email found" })

    interface IService with
        member x.Start () = x.Start ()