Add some debug information to the mssing decoder/encoder exception.

ProtocolLib/src/main/java/com/comphenix/protocol/injector/netty/ChannelInjector.java

@@ -188,7 +188,7 @@ class ChannelInjector extends ByteToMessageDecoder {
 		synchronized (networkManager) {
 			if (originalChannel instanceof Factory)
 				return false;
-			
+
 			// Don't inject the same channel twice
 			if (findChannelHandler(originalChannel, ChannelInjector.class) != null) {
 				// Invalidate cache
@@ -202,9 +202,9 @@ class ChannelInjector extends ByteToMessageDecoder {
 			vanillaEncoder = (MessageToByteEncoder<Object>) originalChannel.pipeline().get("encoder");
 			
 			if (vanillaDecoder == null)
-				throw new IllegalArgumentException("Unable to find vanilla decoder.in " + originalChannel.pipeline());
+				throw new IllegalArgumentException("Unable to find vanilla decoder.in " + originalChannel.pipeline() + ". " + getChannelState());
 			if (vanillaEncoder == null)
-				throw new IllegalArgumentException("Unable to find vanilla encoder in " + originalChannel.pipeline());
+				throw new IllegalArgumentException("Unable to find vanilla encoder in " + originalChannel.pipeline() + ". " + getChannelState());
 			patchEncoder(vanillaEncoder);
 			
 			if (DECODE_BUFFER == null)
@@ -245,6 +245,10 @@ class ChannelInjector extends ByteToMessageDecoder {
 		}
 	}
 	
+	private String getChannelState() {
+		return "Registered channel: " + originalChannel.isRegistered() + ", Active channel: " + originalChannel.isActive() + ", Open channel: " + originalChannel.isOpen();
+	}
+	
 	/**
 	 * Process a given message on the packet listeners.
 	 * @param message - the message/packet.