func filterNil(checkers []echo.Checker) []echo.Checker {
	var out []echo.Checker
	for _, c := range checkers {
		if c != nil {
			out = append(out, c)
		}
	}
	return out
}

// NoError is similar to echo.NoChecker, but provides additional context information.
func NoError() echo.Checker {
	return func(_ echo.CallResult, err error) error {
		if err != nil {
			return fmt.Errorf("expected no error, but encountered %v", err)
		}