Optimize NetworkManager Exception Handling

paper-server/patches/sources/net/minecraft/network/Varint21FrameDecoder.java.patch

@@ -0,0 +1,15 @@
+--- a/net/minecraft/network/Varint21FrameDecoder.java
++++ b/net/minecraft/network/Varint21FrameDecoder.java
+@@ -39,6 +39,12 @@
+     }
+ 
+     protected void decode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, List<Object> list) {
++        // Paper start - Perf: Optimize exception handling; if channel is not active just discard the packet
++        if (!channelHandlerContext.channel().isActive()) {
++            byteBuf.skipBytes(byteBuf.readableBytes());
++            return;
++        }
++        // Paper end - Perf: Optimize exception handling
+         byteBuf.markReaderIndex();
+         this.helperBuf.clear();
+         if (!copyVarint(byteBuf, this.helperBuf)) {