panic(err)
	}
	return res
}

type warningRecorder struct {
	mu       sync.Mutex
	warnings []string
}

// AddWarning adds a warning to recorder.
func (r *warningRecorder) AddWarning(agent, text string) {
	r.mu.Lock()
	defer r.mu.Unlock()
	r.warnings = append(r.warnings, text)
}

func (r *warningRecorder) Warnings() []string {
	r.mu.Lock()