MDX in content collections break on 4.0.4 but works in 4.0.3

[johnjofin07]

Astro Info

Astro                    v5.1.4
Node                     v22.7.0
System                   macOS (arm64)
Package Manager          pnpm
Output                   static
Adapter                  none
Integrations             @astrojs/tailwind
                         @astrojs/react
                         @astrojs/mdx

If this issue only occurs in one browser, which browser is a problem?

No response

Describe the Bug

We were trying to upgrade our astro version from 4 -> 5. We saw some cryptic errors.

Objects are not valid as a React child (found: object with keys {astro:jsx, type, props}). If you meant to render a collection of children, use an array instead.

  Hint:
    This issue often occurs when your MDX component encounters runtime errors.

We narrowed down this issue to @astrojs/mdx 4.0.4. Which was released yesterday,
When we downgraded to 4.0.3 everything was working well.

Our code in blog/[id].astro

---
import BlogLayout from "@/layouts/BlogLayout.astro";
import Layout from "@/layouts/Layout.astro";
import { getCollection, getEntry, render } from "astro:content";
export async function getStaticPaths () {
  const allPosts = await getCollection('articles');
    return allPosts.map(post => ({
        params: {
            id: post.id
        }
    }))
}
// 1. Get the slug from the incoming server request

const { id } = Astro.params;
if (id === undefined) {
  return Astro.redirect("/404");
}
// 2. Query for the entry directly using the request slug
const post = await getEntry("articles", id);
console.log("Post",post)
// 3. Redirect if the entry does not exist
if (post === undefined) {
  return Astro.redirect("/404");
}
// 4. Render the entry to HTML in the template
const { Content } = await render(post);
console.log("Content",Content)
---
<!-- Failing here-->
  <Content/>

What's the expected result?

Blog working

Link to Minimal Reproducible Example

https://github.com/withastro/astro

Participation

• I am willing to submit a pull request for this issue.