twitch: fix npe closing client if no socket has been created

If the client is closed prior to the socket being created, or if socket creation fails, this will repeatedly throw out of close() in connect() and is never able to reestablish a connection

runelite-client/src/main/java/net/runelite/client/plugins/twitch/irc/TwitchIRCClient.java

@@ -67,9 +67,12 @@ public class TwitchIRCClient extends Thread implements AutoCloseable
 	public void close()
 	{
 		try
+		{
+			if (socket != null)
 			{
 				socket.close();
 			}
+		}
 		catch (IOException ex)
 		{
 			log.warn("error closing socket", ex);