My Vercel production build is just outputting the contents of my compiled index.js:

"use strict";  
var __importDefault = (this && this.__importDefault) || function (mod) {  
    return (mod && mod.__esModule) ? mod : { "default": mod };  
};  
Object.defineProperty(exports, "__esModule", { value: true });  
const express_1 = __importDefault(require("express"));  
const fs_1 = __importDefault(require("fs"));  
const path_1 = __importDefault(require("path"));  
require("dotenv/config");  
const posts_1 = require("./posts");  
const app = (0, express_1.default)();  
const PORT = process.env.PORT;  
const postsService = new posts_1.PostsService();  
// Serve static files (CSS, JS, images, etc.)  
app.use("/static", express_1.default.static(path_1.default.join(__dirname, "static")));  
app.get("/", (_, res) => {  
    const homePath = path_1.default.join(__dirname, "home.html");  
    let homeContent = fs_1.default.readFileSync(homePath, "utf8");  
    // Get all posts  
    const posts = postsService.getAllPosts();  
    // Generate HTML for posts  
    const postsHtml = posts.length === 0  
        ? "<p>No posts found.</p>"  
        : posts  
            .map((post) => `<li><a href="${post.url}">${post.title}</a></li>`)  
            .join("");  
    // Replace placeholder in home.html  
    homeContent = homeContent.replace("{{posts}}", postsHtml);  
    res.send(homeContent);  
});  
// Serve individual blog posts (markdown rendered with template)  
app.get("/blog/:slug", (req, res) => {  
    const slug = req.params.slug;  
    const postPath = path_1.default.join(__dirname, "posts", `${slug}.md`);  
    if (fs_1.default.existsSync(postPath)) {  
        try {  
            const postData = postsService.getPostData(`${slug}.md`);  
            const renderedPost = postsService.renderPost(postData);  
            res.send(renderedPost);  
        }  
        catch (error) {  
            console.error("Error rendering post:", error);  
            res  
                .status(500)  
                .send('<h1>Error loading post</h1><a href="/">Back to home</a>');  
        }  
    }  
    else {  
        res  
            .status(404)  
            .send('<h1>Blog post not found</h1><a href="/">Back to home</a>');  
    }  
});  
app.listen(PORT, () => {  
    console.log(`Server is running on port ${PORT}`);  
});  
exports.default = app;  

My vercel.json config file looks like this:

{  
  "$schema": "https://openapi.vercel.sh/vercel.json",  
  "version": 2,  
  "rewrites": [{ "source": "/(.*)", "destination": "/api" }],  
  "outputDirectory": "dist",  
  "devCommand": "npm run dev",  
  "buildCommand": "npm run build"  
}  

I'm using express, and attempting to host a simple blog page. When I run vercel dev locally, it works. I can also npm run dev locally and it works.