Prettier adds extra new lines when run twice on mdx with inline tags

[emckay]

Prettier 1.18.2
Playground link

--parser mdx
--prose-wrap always

Input:

This is a fairly long sentence with an html tag near the <dfn data-title="testing">end</dfn> and then some additional words.

Output:

This is a fairly long sentence with an html tag near the
<dfn data-title="testing">end</dfn> and then some additional words.

Second Output:

SyntaxError: Unexpected token (1:37)
> 1 | <dfn data-title="testing">end</dfn> and then some additional words.
    |                                     ^

Expected behavior:

The output from this sample might be fine, but after prettier runs on it again, it throws an error in the playground: Playground link

This seems to be an error specific to the playground. Locally, when I run prettier@1.18.2 twice over the sample text, this is what I get:

$ yarn list --pattern prettier
yarn list v1.12.3
└─ prettier@1.18.2
Done in 0.84s.
$ echo "This is a fairly long sentence with an html tag near the <dfn data-title="testing">end</dfn> and then some additional words." | yarn run --silent prettier --parser mdx --prose-wrap always | yarn run --silent prettier --parser mdx --prose-wrap always
This is a fairly long sentence with an html tag near the

<dfn data-title=testing>end</dfn> and then some additional words.

The extra new line causes the markdown parser to break up what was originally a single line into two paragraphs.

[gutenye]

@fisker This bug is annoying, any plans to fix it?

[kachkaev]

Worth tracking #12209 (help wanted!)