An error occurs with certain text when using `remarkMath` and `rehypeKatex`.

[devleejb]

Initial checklist

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

Affected packages and versions

react-markdown:9.0.1

Link to runnable example

No response

Steps to reproduce

1. Implement the following code. (Node 18, npm 10)

   <Markdown
       remarkPlugins={[remarkMath]}
       rehypePlugins={[rehypeKatex]}
   >
     {`$\\begin\\ca$`}
   </Markdown>

2. Run the code.
3. Check for any errors.

Expected behavior

It should render the markdown text correctly.

Actual behavior

Following error occurs.

Runtime

Other (please specify in steps to reproduce)

Package manager

Other (please specify in steps to reproduce)

OS

macOS

Build and bundle tools

Vite

[wooorm]

This looks like a KaTeX problem, why not raise it with KaTeX? Why raise it here? Do you think there is something to change here?

[devleejb]

@wooorm At first, I thought that it is a KaTex problem. But, when I run the following code, it runs correctly.

const file = await unified()
  .use(remarkParse)
  .use(remarkMath)
  .use(remarkRehype)
  .use(rehypeKatex)
  .use(rehypeStringify)
  .process(`$\\begin\\ca$`)

[wooorm]

Cannot reproduce:

import {unified} from 'unified'
import remarkParse from 'remark-parse'
import remarkMath from 'remark-math'
import remarkRehype from 'remark-rehype'
import rehypeKatex from 'rehype-katex'
import rehypeStringify from 'rehype-stringify'

const file = await unified()
  .use(remarkParse)
  .use(remarkMath)
  .use(remarkRehype)
  .use(rehypeKatex)
  .use(rehypeStringify)
  .process(`$\\begin\\ca$`)

console.log(String(file))

file:///Users/tilde/Projects/oss/react-markdown/node_modules/katex/dist/katex.mjs:7482
    throw new Error("Expected node of type " + type + ", but got " + (node ? "node of type " + node.type : String(node)));
          ^

Error: Expected node of type textord, but got node of type color
    at assertNodeType (file:///Users/tilde/Projects/oss/react-markdown/node_modules/katex/dist/katex.mjs:7482:11)
    at Object.handler (file:///Users/tilde/Projects/oss/react-markdown/node_modules/katex/dist/katex.mjs:11491:18)
    at Parser.callFunction (file:///Users/tilde/Projects/oss/react-markdown/node_modules/katex/dist/katex.mjs:17637:19)
    at Parser.parseFunction (file:///Users/tilde/Projects/oss/react-markdown/node_modules/katex/dist/katex.mjs:17620:17)
    at Parser.parseGroup (file:///Users/tilde/Projects/oss/react-markdown/node_modules/katex/dist/katex.mjs:18012:21)
    at Parser.parseAtom (file:///Users/tilde/Projects/oss/react-markdown/node_modules/katex/dist/katex.mjs:17450:21)
    at Parser.parseExpression (file:///Users/tilde/Projects/oss/react-markdown/node_modules/katex/dist/katex.mjs:17312:23)
    at Parser.parse (file:///Users/tilde/Projects/oss/react-markdown/node_modules/katex/dist/katex.mjs:17244:24)
    at parseTree (file:///Users/tilde/Projects/oss/react-markdown/node_modules/katex/dist/katex.mjs:18247:21)
    at renderToDomTree (file:///Users/tilde/Projects/oss/react-markdown/node_modules/katex/dist/katex.mjs:18337:16)

As in: there’s definitely a KaTeX error, when using the latest dependencies otherwise.

Now, rehype-katex also has a problem. It should catch that error.

[devleejb]

@wooorm Okay. Sorry, I'll check it again and raise it in KaTeX.

[wooorm]

OK, if you believe that math input to be valid for KaTeX.

I’ll also work on a fix in rehype-katex to swallow that error and display the raw input instead of crashing.

[wooorm]

In rehype-katex I am getting this error btw:

ParseError: KaTeX parse error: Undefined control sequence: \ca at position 7: \begin\̲c̲a̲
    at new ParseError (file:///Users/tilde/Projects/oss/remark-math/node_modules/katex/dist/katex.mjs:147:16)
    at Parser.parseGroup (file:///Users/tilde/Projects/oss/remark-math/node_modules/katex/dist/katex.mjs:18016:17)
    at Parser.parseAtom (file:///Users/tilde/Projects/oss/remark-math/node_modules/katex/dist/katex.mjs:17450:21)
    at Parser.parseExpression (file:///Users/tilde/Projects/oss/remark-math/node_modules/katex/dist/katex.mjs:17312:23)
    at Parser.parseArgumentGroup (file:///Users/tilde/Projects/oss/remark-math/node_modules/katex/dist/katex.mjs:17955:27)
    at Parser.parseGroupOfType (file:///Users/tilde/Projects/oss/remark-math/node_modules/katex/dist/katex.mjs:17705:21)
    at Parser.parseArguments (file:///Users/tilde/Projects/oss/remark-math/node_modules/katex/dist/katex.mjs:17670:22)
    at Parser.parseFunction (file:///Users/tilde/Projects/oss/remark-math/node_modules/katex/dist/katex.mjs:17619:14)
    at Parser.parseGroup (file:///Users/tilde/Projects/oss/remark-math/node_modules/katex/dist/katex.mjs:18012:21)
    at Parser.parseAtom (file:///Users/tilde/Projects/oss/remark-math/node_modules/katex/dist/katex.mjs:17450:21) {
  position: 6,
  length: 3,
  rawMessage: 'Undefined control sequence: \\ca'
}

So could be that that is the root problem

[github-actions[bot]]

Hi! This was closed. Team: If this was fixed, please add phase/solved. Otherwise, please add one of the no/* labels.

[github-actions[bot]]

Hi team! Could you describe why this has been marked as external?

Thanks, — bb