fix(proxy): don't send packets to a client when client server is null

proxy/changelog.md

@@ -6,4 +6,5 @@ Versions 2.0.x and 2.1.x are protocol-compatible,
 so there’s no need to worry if the server hasn't been updated to 2.1.x.
 
 ### Changes in 2.1.2
-- Fixed buffer overflow when using AudioSender with delayed first frame.
+- Fixed buffer overflow when using AudioSender with delayed first frame.
+- Fixed client EncoderException on server switch caused by UDP packets sent to a client when client's server is null.  

proxy/common/src/main/java/su/plo/voice/proxy/socket/NettyPacketHandler.java

@@ -128,6 +128,8 @@ private boolean sendPacket(ChannelHandlerContext ctx, NettyPacketUdp nettyPacket
         } else {
             receiver = connection.getRemoteAddress();
             receiverSecret = connection.getSecret();
+
+            if (!connection.isConnected()) return true;
         }
 
         // rewrite to backend server

proxy/common/src/main/java/su/plo/voice/proxy/socket/NettyUdpProxyConnection.java

@@ -42,7 +42,6 @@ public final class NettyUdpProxyConnection implements UdpProxyConnection, Server
     private InetSocketAddress remoteAddress;
     @Setter
     private RemoteServer remoteServer;
-    @Getter
     private boolean connected = true;
 
     @Override
@@ -52,6 +51,8 @@ public Optional<RemoteServer> getRemoteServer() {
 
     @Override
     public void sendPacket(Packet<?> packet) {
+        if (!isConnected()) return;
+
         byte[] encoded = PacketUdpCodec.encode(packet, secret);
         if (encoded == null) return;
 
@@ -70,6 +71,11 @@ public void disconnect() {
         this.connected = false;
     }
 
+    @Override
+    public boolean isConnected() {
+        return connected && player.getInstance().getServer() != null;
+    }
+
     @Override
     public void handle(@NotNull PingPacket packet) {
     }