MessageEvent err

// Payload.ts

export interface Payload {
    op: OP;
    d?: string;
    s?: number;
    t?: string;
}

// WebSocketManager.ts

import { Payload, OP } from '../models/Payload.ts'

export default class WebSocketManager {
    private _ws!: WebSocket;

    connect(token: string) {
        this._ws = new WebSocket("wss://gateway.discord.gg/?v=8&encoding=json");

        this._ws.onmessage = this._message;
    }

    close() {
        console.log("closing the socket...");
        this._ws.close(1);
    }

    private _message({ data }: MessageEvent<Payload>) {
        console.log(data.d, data.t, data.s, data.op); // <--- HERE ERROR
        // undefined undefined undefined undefined
    }
}