rehype-katex: can't hanlde \end{cases}$$

[steve02081504]

Initial checklist

• I read the support docs
• I read the contributing guide
• I agree to follow the code of conduct
• I searched issues and discussions and couldn’t find anything (or linked relevant results below)

Affected package

rehype-katex

Steps to reproduce

code: https://github.com/steve02081504/fount/blob/0183423e52859c93fa26b910028f43a9e8380365/src/public/scripts/markdown.mjs#L32
not work:

$$\begin{cases}
h(0) = 0 \\
h'(0) = 1
\end{cases}$$

works:

$$
\begin{cases}
h(0) = 0 \\
h'(0) = 1
\end{cases}
$$

Actual behavior

not work: ParseError: KaTeX parse error: Expected 'EOF', got '\end' at position 23: …0 \\ h'(0) = 1 \̲e̲n̲d̲{cases}$$

Expected behavior

should work

Runtime

firefox dev

Package manager

No response

Operating system

No response

Build and bundle tools

No response

[ChristianMurphy]

Math blocks work like code blocks.
They are expected to be on newline by themselves.

There is a more technical explanation in the syntax guide.
https://github.com/micromark/micromark-extension-math#syntax