fix(client): don't send packets to a server when Minecraft connection…

… is null aka in config/login state

client/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 EncoderException on server switch on servers with proxy and proxy-side addons (e.g, groups addon).

client/src/main/java/su/plo/voice/client/connection/ModServerConnection.java

@@ -121,7 +121,7 @@ public ModServerConnection(@NotNull BaseVoiceClient voiceClient,
 
     @Override
     public void sendPacket(@NotNull Packet<?> packet, boolean checkUdpConnection) {
-        if (!connection.isConnected()) return;
+        if (!connection.isConnected() || Minecraft.getInstance().getConnection() == null) return;
 
         if (checkUdpConnection && !voiceClient.getUdpClientManager().isConnected())
             return;