use errors.As

[zaneli]

Now, wrapped errors are always handle as 500.
I want to fix it.

import (
  "golang.org/x/xerrors"
  routing "github.com/qiangxue/fasthttp-routing"
  "github.com/valyala/fasthttp"
)

  ...
  err := routing.NewHTTPError(fasthttp.StatusBadRequest)
  return xerrors.Errorf("bad request: %w", err)