Fix removing cached player from new node instead of old

Also manages the LinkState a bit more consistently

Author: freyacodes

src/main/kotlin/dev/arbjerg/lavalink/client/LavalinkClient.kt

@@ -187,8 +187,6 @@ class LavalinkClient(val userId: Long) : Closeable, Disposable {
         linkMap.forEach { (_, link) ->
             if (link.node == node) {
                 val voiceRegion = link.cachedPlayer?.voiceRegion
-
-                link.state = LinkState.CONNECTING
                 // The delay is used to prevent a race condition in Discord, causing close code 4006
                 link.transferNode(loadBalancer.selectNode(region = voiceRegion, link.guildId), delay = Duration.ofMillis(1000))
             }

src/main/kotlin/dev/arbjerg/lavalink/client/LavalinkNode.kt

@@ -427,6 +427,8 @@ class LavalinkNode(
      */
     fun getCachedPlayer(guildId: Long): LavalinkPlayer? = playerCache[guildId]
 
+    internal fun getAndRemoveCachedPlayer(guildId: Long): LavalinkPlayer? = playerCache.remove(guildId)
+
     /**
      * @return an unmodifiable view of all cached players for this node.
      */

src/main/kotlin/dev/arbjerg/lavalink/client/Link.kt

@@ -58,18 +58,19 @@ class Link(
     fun loadItem(identifier: String) = node.loadItem(identifier)
 
     internal fun transferNode(newNode: LavalinkNode, delay: Duration = Duration.ZERO) {
-        val player = node.getCachedPlayer(guildId)
+        val player = node.getAndRemoveCachedPlayer(guildId)
 
         if (player != null) {
+            state = LinkState.CONNECTING
             newNode.createOrUpdatePlayer(guildId)
                 .applyBuilder(player.stateToBuilder())
                 .delaySubscription(delay)
-                .subscribe({
-                    node.removeCachedPlayer(guildId)
-                }) {
+                .doOnError {
                     state = LinkState.DISCONNECTED
                     logger.error("Failed to transfer player to new node: ${newNode.name}", it)
-                }
+                }.subscribe()
+        } else {
+            state = LinkState.DISCONNECTED
         }
 
         node = newNode