anchor.diff:                          Seq.append folders files
                   else
                       if path.Drive |> Option.exists (fun d -> not <| DriveInfo(wpath d).IsReady) then
  -                        Error <| Exception "Drive is not ready"
  +                        Error <| exn "Drive is not ready"
                       else
  -                        Error <| Exception "Path does not exist"
  +                        Error <| exn (sprintf "Path does not exist: %s" (wpath path))
           allNodes |> Result.map (fun allNodes ->
               let nodes =
                   allNodes
  
positive.code:                 path.Drive
                  |> Option.map (fun d -> DriveInfo(wpath d).TotalSize)
                  |> Option.filter (flip (>) 0L)
                  |> Result.ofOption (Exception "This drive does not have a recycle bin.")
              let! node = this.GetNode path
              let! size =
                  match node with
  
negative.code:         match this.GetNode path with
          | Ok (Some node) when node.Type = File || node.Type = Folder -> action node.Type
          | Ok (Some node) -> Error <| cannotActOnNodeType actionName node.Type
          | Ok None -> Error <| exn (sprintf "Path does not exist: %s" (wpath path))
          | Error e -> Error e
  
      interface IFileSystemReader with
  