)

var userTypeCache sync.Map // map[reflect.Type]*userTypeInfo

// validUserType returns, and saves, the information associated with user-provided type rt.
// If the user type is not valid, err will be non-nil. To be used when the error handler
// is not set up.
func validUserType(rt reflect.Type) (*userTypeInfo, error) {
	if ui, ok := userTypeCache.Load(rt); ok {
		return ui.(*userTypeInfo), nil
	}