Client emit or send, nothing cames to server #790

[marktech0813]

I added a defensive improvement and documentation to address your issue.

• In Socket.emit(...), the client now logs a warning if you emit a JSON-looking string (e.g., "{...}" or "[...]"), prompting you to send a JSONObject/JSONArray instead.
• In src/site/markdown/emitting_events.md, I documented this pitfall with a “wrong vs correct” example.