func NewNPErr(err error) (NoPayload, *RemoteErr) {
	if err == nil {
		return NoPayload{}, nil
	}
	r := RemoteErr(err.Error())
	return NoPayload{}, &r
}

// NewRemoteErrString creates a new remote error from a string.
func NewRemoteErrString(msg string) *RemoteErr {
	r := RemoteErr(msg)
	return &r
}

func (r RemoteErr) Error() string {
	return string(r)
}

				var n byte
				<-processHandler
				for {
					select {
					case in, ok := <-request:
						if !ok {
							return nil
						}
						if in[0] != n {
							return NewRemoteErrString(fmt.Sprintf("expected incoming %d, got %d", n, in[0]))
						}
						n++
						resp <- append([]byte{}, in...)
					case <-ctx.Done():
						return NewRemoteErr(ctx.Err())
					}
				}
			},

	if !s.checkID(params.DiskID) {
		return grid.NewRemoteErr(errDiskNotFound)
	}
	if params.Cache == nil {
		return grid.NewRemoteErrString("NSScannerHandler: provided cache is nil")
	}

	// Collect updates, stream them before the full cache is sent.
	updates := make(chan dataUsageEntry, 1)
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {

		var start time.Time
		if m.DeadlineMS > 0 {
			start = time.Now()
		}
		var b []byte
		var err *RemoteErr
		func() {
			defer func() {
				if rec := recover(); rec != nil {
					err = NewRemoteErrString(fmt.Sprintf("handleMessages: panic recovered: %v", rec))
					debug.PrintStack()
					gridLogIf(ctx, err)
				}
			}()
			b, err = handler(m.Payload)
			if debugPrint {