🐛 BUG: Astro extension and mdx extension working at the same time causes mdx highlighting error.

[liruifengv]

Describe the Bug

Astro extension and mdx extension working at the same time causes mdx highlighting error.

I installed version 2.10.2 and everything works fine, when installing a version larger than 2.11, I get a highlighting error.

2.10.2

2.11

I think the problem may be related to this PR: #878

Steps to Reproduce

1. Installing the Astro extension and the mdx extension in VSCode at the same time
2. Open our docs repository and open the api-reference.mdx page.
3. Then you can see the highlighting error

Link to Minimal Reproducible Example

https://github.com/withastro/docs/blob/main/src/content/docs/en/reference/api-reference.mdx

[ArmandPhilippot]

I don't know if this is always the case, but highlighting seems to break due to fenced codes that use astro language. For example in src/content/docs/en/reference/api-reference.mdx if you do the following change at line 17:

-```astro
+```

You'll see that the next lines are correctly highlighted until the next code block that uses astro as language (while having both extensions enabled).