io.netty.handler.codec.EncoderException when using special characters in chat message

When typing a chat message that contains a special character on a server with chat preview enabled, an exception will occur and you get disconnected.

 

Steps to reproduce:

1. Join a server with chat preview enabled.
2. Type any letter until you can't type anymore.
3. Press backspace once.
4. Type a special character like a "☺" for example.
5. Observe disconnect.

See client log attached: