Silent build errors on malformed multiline comments

[leemthompo]

What happened

Build silently stops rendering content after malformed multiline comment. No error thrown, no warning. Everything after the comment is dropped from output.

Expected behavior

Should either:

• Throw build error on malformed comment syntax
• Render entire page regardless

Actual behavior

• Page cuts off at malformed comment
• "On this page" nav is rendered
• Subsequent actual errors in page go undetected
• Build completes successfully despite broken output

Screenshots

What it looked like

What it should have looked like

Inciting PR

I took a couple of commits (starting with c4f53ba) to diagnose the actual issue (at first I thought it was bugging on using two comment syntaxes at once)

Syntax issue

Bad syntax (causes silent failure):

<!-- :::{note}
TODO: Uncomment once page is live.
The chat UI is available in both standalone and flyout modes. For more information, refer to [Chat UI modes](standalone-and-flyout-modes.md).
::: -->

Good syntax (works):

<!--
:::{note}
TODO: Uncomment once page is live.
The chat UI is available in both standalone and flyout modes. For more information, refer to [Chat UI modes](standalone-and-flyout-modes.md).
:::
-->