Here's the code.

"use server";

import ReactPDF from "@react-pdf/renderer";

import graph from "@/server/graph";
import ScenarioGuide from "@/server/pdfs/ScenarioGuide";

// https://stackoverflow.com/a/63361543
async function streamToBase64(stream) {
    const chunks = [];

    for await (const chunk of stream) {
        chunks.push(Buffer.from(chunk));
    }

    return Buffer.concat(chunks).toString("base64");
}

export default async function createQuiz(req, res) {
    const recruiterEmail = "*";

    await graph.sendEmail(recruiterEmail, {
        attachments: [
            await graph.createAttachment("Scenario Guide.pdf", {
                skipAutoFetchFile: true,
                isInline: false,
                contentBytes: await streamToBase64(
                    await ReactPDF.renderToStream(
                        <ScenarioGuide
                            quizCreationDate={new Date()}
                            recruiterName="Name"
                            recruiterEmail={recruiterEmail}
                            scenarioNames={["Derek", "Margaret", "Mr Singh"]}
                        />,
                    ),
                ),
                contentId: undefined,
                contentType: "application/pdf",
            }),
        ],
        subject: "Subject",
        content: "Check attachments.",
    });

    res.status(200).end();
}

Before I didn't have the "use server" directive, and it spat out a Webpack error saying "fs" couldn't be found for some reason.

And here's my Next config:

import path from "path";
import process from "process";

import NextBundleAnalyzer from "@next/bundle-analyzer";

import config from "./src/server/config.js";

const withBundleAnalyzer = NextBundleAnalyzer({
    enabled: config.ANALYZE ?? false,
});

/**
 * @type {import('next').NextConfig}
 **/
export default withBundleAnalyzer({
    // NGinx is configured to automatically compress contents to GZip
    compress: false,
    reactStrictMode: true,
    // TODO: Revert this when you're done converting to TS
    typescript: {
        ignoreBuildErrors: true,
    },

    // TODO: Revert this when you're done converting to TS
    webpack(config) {
        return {
            ...config,
            experiments: {
                ...config.experiments,
                topLevelAwait: true,
            },
            resolve: {
                ...config.resolve,
                alias: {
                    ...config.resolve.alias,
                    "@": path.resolve("./src"),
                },
            },
        };
    },
});

Sorry there's so much to digest, I literally can't figure out what the issue is and the errors make no sense. I've added packages, removed packages, changed runtimes and nothing.

Bump.

Got some sleep and am wondering if the issue is me using Puppeteer + Handlebars to generate emails, so might have to rewrite them using React Email.