Email Workers Playground error and dropped emails

import { EmailMessage } from "cloudflare:email";
import { createMimeMessage } from "mimetext";

export default {
    async email(message, env, ctx) {
        const msg = createMimeMessage();
        msg.setHeader("In-Reply-To", message.headers.get("Message-ID"));
        msg.setSender({ name: "noreply", addr: "noreply@xxx.ch" });
        msg.setRecipient(message.from);
        msg.setSubject("Email Routing Auto-reply");
        msg.addMessage({
            contentType: "text/plain",
            data: `Hello
      This is an automated reply to your email.`,
        });

        await fetch("https://discord.com/api/webhooks/xxx", {
            method: "post",
            headers: {
                "Content-Type": "application/json",
            },
            body: JSON.stringify({
                username: "webhook",
                content: `${msg.asRaw()}`,
            }),
        });

        var replyMessage = new EmailMessage(
            "noreply@xxx.ch",
            message.from,
            msg.asRaw()
        );

        message.reply(replyMessage);
    },
};