Bug: json.Marshal error ignored in hysteria2 realm_server SSE event stream

[hklcf]

Description

In protocol/hysteria2/realm_server.go:383, the error from json.Marshal is silently ignored:

data, _ := json.Marshal(ev.data)
fmt.Fprintf(w, "event: %s\ndata: %s\n\n", ev.kind, data)

Impact

If ev.data contains values that cannot be serialized by encoding/json (e.g., channels, functions, complex numbers, or cyclic data structures), the marshal will silently return an empty byte slice or incomplete JSON. The SSE stream will then send malformed data, and the client will receive corrupted or empty events with no indication of the error.

Location

protocol/hysteria2/realm_server.go:383

Suggested Fix

At minimum, log the error and skip the event:

data, err := json.Marshal(ev.data)
if err != nil {
    return
}
fmt.Fprintf(w, "event: %s\ndata: %s\n\n", ev.kind, data)