error_handler.ex

case get_format(conn) do
  "json" ->
    cond do
      kind == :error ->
        case reason.__struct__ do
          Ecto.NoResultsError ->
            error_view = "404.json"

          App.Utils.Error.NotFound ->
            error_view = "404.json"

          App.Utils.Error.RequestInvalid ->
            error_view = "400.json"

          App.Utils.Error.Unauthenticated ->
            error_view = "401.json"

          App.Utils.Error.PermissionDenied ->
            error_view = "403.json"

          App.Utils.Error.InternalServerError ->
            error_view = "500.json"

          _ ->
            error_view = "500.json"
            App.Manager.UserManager.send_email_error("#{inspect stack}")
        end
        conn
          |> render(App.Api.ErrorView, error_view, fields: reason)
      true ->
        App.Manager.UserManager.send_email_error("#{inspect stack}")
        conn
            |> render(App.Api.ErrorView, "500.json", fields: reason)
    end
  "html" ->
    cond do
      kind == :error ->
        case reason.__struct__ do
          Ecto.NoResultsError ->
            error_view = "404.html"

          App.Utils.Error.NotFound ->
            error_view = "404.html"

          App.Utils.Error.RequestInvalid ->
            error_view = "400.html"

          App.Utils.Error.Unauthenticated ->
            error_view = "401.html"

          App.Utils.Error.PermissionDenied ->
            error_view = "403.html"

          App.Utils.Error.InternalServerError ->
            error_view = "500.html"

          _ ->
            error_view = "500.html"
            App.Manager.UserManager.send_email_error("#{inspect stack}")

        end
        conn
          |> put_view(App.Frontend.ErrorView)
          |> render(error_view)
      true ->
            App.Manager.UserManager.send_email_error("#{inspect stack}")
        conn
          |> put_view(App.Frontend.ErrorView)
          |> render("500.html")
    end
  _ ->
    conn
      |> put_view(App.Frontend.ErrorView)
      |> render("404.html")
end