Protect against incorrect temporal layer. (#4327)

Seeing some tracks with temporal layer higher than array bounds.
Protect against it and log some info to understand better.

pkg/sfu/streamtracker/streamtracker.go

@@ -69,8 +69,8 @@ type StreamTracker struct {
 	lastNotifiedStatus StreamStatus
 
 	lastBitrateReport time.Time
-	bytesForBitrate   [4]int64
-	bitrate           [4]int64
+	bytesForBitrate   [buffer.DefaultMaxLayerTemporal + 1]int64
+	bitrate           [buffer.DefaultMaxLayerTemporal + 1]int64
 
 	isStopped bool
 }
@@ -207,8 +207,17 @@ func (s *StreamTracker) Observe(
 		go s.worker(s.generation.Load())
 	}
 
-	if temporalLayer >= 0 {
+	if temporalLayer >= 0 && int(temporalLayer) < len(s.bytesForBitrate) {
 		s.bytesForBitrate[temporalLayer] += int64(pktSize)
+	} else if int(temporalLayer) >= len(s.bytesForBitrate) {
+		s.params.Logger.Warnw(
+			"invalid temporal layer", nil,
+			"temporalLayer", temporalLayer,
+			"pktSize", pktSize,
+			"payloadSize", payloadSize,
+			"hasMarker", hasMarker,
+			"ts", ts,
+		)
 	}
 	s.lock.Unlock()