Add state in exception message (#10842)

Motivation:
We should add `state` in the exception message of `HttpObjectEncoder` because it makes debugging a little easier.

Modification:
Added `state` in the exception message.

Result:
Better exception message for smooth debugging.

codec-http/src/main/java/io/netty/handler/codec/http/HttpObjectEncoder.java

@@ -121,7 +121,8 @@ public abstract class HttpObjectEncoder<H extends HttpMessage> extends MessageTo
         if (msg instanceof HttpContent || msg instanceof ByteBuf || msg instanceof FileRegion) {
             switch (state) {
                 case ST_INIT:
-                    throw new IllegalStateException("unexpected message type: " + StringUtil.simpleClassName(msg));
+                    throw new IllegalStateException("unexpected message type: " + StringUtil.simpleClassName(msg)
+                        + ", state: " + state);
                 case ST_CONTENT_NON_CHUNK:
                     final long contentLength = contentLength(msg);
                     if (contentLength > 0) {