move score starting nil check inside the score implementation

gossipsub.go

@@ -184,10 +184,8 @@ func (gs *GossipSubRouter) Attach(p *PubSub) {
 	gs.p = p
 	gs.tracer = p.tracer
 
-	// start the scoring, if any
-	if gs.score != nil {
-		gs.score.Start(gs)
-	}
+	// start the scoring
+	gs.score.Start(gs)
 
 	// start using the same msg ID function as PubSub for caching messages.
 	gs.mcache.SetMsgIdFn(p.msgID)

score.go

@@ -294,6 +294,10 @@ func (p *TopicScoreParams) validate() error {
 
 // router interface
 func (ps *peerScore) Start(gs *GossipSubRouter) {
+	if ps == nil {
+		return
+	}
+
 	ps.msgID = gs.p.msgID
 	ps.host = gs.p.host
 	go ps.background(gs.p.ctx)