Handle node removal better to ensure players aren't used if there's no node

go.mod

@@ -1,6 +1,7 @@
 module meow.tf/astra/gavalink
 
 require (
+	github.com/bwmarrin/discordgo v0.20.3 // indirect
 	github.com/foxbot/gavalink v0.0.0-20181105223750-6252b1245300
 	github.com/gorilla/websocket v1.4.0
 	github.com/valyala/fastjson v1.4.1

go.sum

@@ -1,6 +1,10 @@
+github.com/bwmarrin/discordgo v0.20.3 h1:AxjcHGbyBFSC0a3Zx5nDQwbOjU7xai5dXjRnZ0YB7nU=
+github.com/bwmarrin/discordgo v0.20.3/go.mod h1:O9S4p+ofTFwB02em7jkpkV8M3R0/PUVOwN61zSZ0r4Q=
 github.com/foxbot/gavalink v0.0.0-20181105223750-6252b1245300 h1:/p4AzwhPqvi9V0Ktsd+4jpkTpkLbrns2AyCUrylJFDo=
 github.com/foxbot/gavalink v0.0.0-20181105223750-6252b1245300/go.mod h1:MDlIQ50PLaU0fUW0JcHFOxec8Q17F9byrnGi8ok5vVQ=
 github.com/gorilla/websocket v1.4.0 h1:WDFjx/TMzVgy9VdMMQi2K2Emtwi2QcUQsztZ/zLaH/Q=
 github.com/gorilla/websocket v1.4.0/go.mod h1:E7qHFY5m1UJ88s3WnNqhKjPHQ0heANvMoAMk2YaljkQ=
 github.com/valyala/fastjson v1.4.1 h1:hrltpHpIpkaxll8QltMU8c3QZ5+qIiCL8yKqPFJI/yE=
 github.com/valyala/fastjson v1.4.1/go.mod h1:nV6MsjxL2IMJQUoHDIrjEI7oLyeqK6aBD7EFWPsvP8o=
+golang.org/x/crypto v0.0.0-20181030102418-4d3f4d9ffa16 h1:y6ce7gCWtnH+m3dCjzQ1PCuwl28DDIc3VNnvY29DlIA=
+golang.org/x/crypto v0.0.0-20181030102418-4d3f4d9ffa16/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=

lavalink.go

@@ -117,12 +117,17 @@ func (l *Lavalink) removeNode(node *Node) error {
 
 	node.stop()
 
+	danglingPlayers := make([]*Player, 0)
+
 	l.playersMu.RLock()
 	for _, player := range l.players {
 		if player.node == node {
+			player.node = nil
+
 			n, err := l.BestNode()
 
-			if err != nil {
+			if err != nil || n == nil {
+				danglingPlayers = append(danglingPlayers, player)
 				continue
 			}
 
@@ -131,6 +136,12 @@ func (l *Lavalink) removeNode(node *Node) error {
 	}
 	l.playersMu.RUnlock()
 
+	if len(danglingPlayers) > 0 {
+		for _, player := range danglingPlayers {
+			player.Destroy()
+		}
+	}
+
 	// temp var for easier reading
 	n := l.nodes
 	z := len(n) - 1

player.go

@@ -191,15 +191,14 @@ func (player *Player) ChangeNode(node *Node) error {
 
 // Destroy will destroy this player
 func (player *Player) Destroy() error {
-	msg := basicMessage{
-		Op:      opDestroy,
-		GuildID: player.guildID,
-	}
+	if player.node != nil && player.node.wsConn != nil {
+		msg := basicMessage{
+			Op:      opDestroy,
+			GuildID: player.guildID,
+		}
 
-	err := player.node.wsConn.WriteJSON(msg)
-
-	if err != nil {
-		return err
+		// We don't actually care if this goes through, since the node/connection may be invalid anyway.
+		player.node.wsConn.WriteJSON(msg)
 	}
 
 	player.manager.playersMu.Lock()