wooorm/xdm is no longer maintained, switch to mdx-js/mdx

[marcofranssen]

See https://www.npmjs.com/package/xdm

Following is stated in the README.md.

xdm was a fork (complete rewrite?) that envisioned how [mdx-js/mdx](https://github.com/mdx-js/mdx) could work.
All of xdm has now been ported into mdx-js/mdx making xdm no longer needed. Use mdx-js/mdx instead.

Hopefully this also resolves some issues I'm facing with unsupported markdown.

I'm using currently next-mdx-remote. I'm trying to migrate this to mdx-bundler (used by contentlayer).

The problem I'm facing is with some basic markdown support. E.g.:

Following is supported with next-mdx-remote:

This is some markdown with a shorthand syntax for urls <https://marcofranssen.nl>.
This is shorter then doing the full syntax like [https://marcofranssen.nl](https://marcofranssen.nl)
for the cases where my link text equals the hyperlink itself.

With mdx-bundler it fails with following errors.

[plugin esbuild-xdm] Unexpected character `/` (U+002F) before local name, expected a character that can start a name, such as a letter, `$`, or `_` (note: to create a link in MDX, use `[text](url)`)

    _mdx_bundler_entry_point-a47d6815-08af-475d-9612-5ba18b1abaae.mdx:172:7:
      172 │ <https://marcofranssen.nl>

If this isn't related, please let me know if I should file this as a separate issue.

[n18l]

I can't speak specifically to your unsupported markdown issues, but do the existing efforts to migrate over to MDX v2 (#137 and #152) otherwise cover the issue as titled?