From 53382c5774705981030537b1d622e57fb11cd568 Mon Sep 17 00:00:00 2001
From: Saxon <saxon@ausocean.org>
Date: Tue, 12 Mar 2019 15:39:51 +1030
Subject: [PATCH] revid: newMultiSender returns error if the passed active
 function is nil

---
 revid/revid.go   | 7 +++++--
 revid/senders.go | 8 ++++++--
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/revid/revid.go b/revid/revid.go
index 063a2aeb..43782a71 100644
--- a/revid/revid.go
+++ b/revid/revid.go
@@ -219,7 +219,10 @@ func (r *Revid) reset(config Config) error {
 		if len(mtsSenders) != 1 && len(flvSenders) != 0 {
 			retry = false
 		}
-		ms := newMultiSender(mtsSenders, retry, r.IsRunning)
+		ms, _ := newMultiSender(mtsSenders, retry, r.IsRunning)
+		if err != nil {
+			return err
+		}
 		e := mts.NewEncoder(ms, float64(r.config.FrameRate))
 		r.encoder = append(r.encoder, e)
 	}
@@ -228,7 +231,7 @@ func (r *Revid) reset(config Config) error {
 	// encoder to revid's encoder slice, and give this encoder the flvSenders
 	// as a destination.
 	if len(flvSenders) != 0 {
-		ms := newMultiSender(flvSenders, false, r.IsRunning)
+		ms, _ := newMultiSender(flvSenders, false, r.IsRunning)
 		e, err := flv.NewEncoder(ms, true, true, int(r.config.FrameRate))
 		if err != nil {
 			return err
diff --git a/revid/senders.go b/revid/senders.go
index ee7e5b18..0dc40e9c 100644
--- a/revid/senders.go
+++ b/revid/senders.go
@@ -63,12 +63,16 @@ type multiSender struct {
 // newMultiSender returns a pointer to a new multiSender. active is a function
 // to indicate the state of the multiSenders owner i.e. whether it is running
 // or not.
-func newMultiSender(senders []loadSender, retry bool, active func() bool) *multiSender {
-	return &multiSender{
+func newMultiSender(senders []loadSender, retry bool, active func() bool) (*multiSender, error) {
+	if active == nil {
+		return nil, errors.New("multi sender requires that active func is provided")
+	}
+	s := &multiSender{
 		senders: senders,
 		retry:   retry,
 		active:  active,
 	}
+	return s, nil
 }
 
 // Write implements io.Writer. The written slice will be sent to each loadSender