code: func renderErr(c *router.Context, err error) {
  	status := grpcCodeToHTTP[grpc.Code(err)]
  	if status == 0 {
  		status = http.StatusInternalServerError
  	}
  	c.Writer.Header().Set("Content-Type", "text/html; charset=utf-8")
  	c.Writer.WriteHeader(status)
  	templates.MustRender(c.Context, c.Writer, "pages/error.html", map[string]interface{}{
  		"Message": err.Error(),
  	})
  }
docs: // renderErr renders a page with error message.