rehype-katex: fix crash on katex error

Closes remarkjs/react-markdown#853.

packages/rehype-katex/lib/index.js

@@ -101,18 +101,19 @@ export default function rehypeKatex(options) {
  source: 'rehype-katex'
  })
 
- // KaTeX can handle `ParseError` itself, but not others.
- if (ruleId === 'parseerror') {
+ // KaTeX *should* handle `ParseError` itself, but not others.
+ // it doesn’t always:
+ // <https://github.com/remarkjs/react-markdown/issues/853>
+ try {
  result = katex.renderToString(value, {
  ...settings,
  displayMode,
  strict: 'ignore',
  throwOnError: false
  })
- }
- // Generate similar markup if this is an other error.
- // See: <https://github.com/KaTeX/KaTeX/blob/5dc7af0/docs/error.md>.
- else {
+ } catch {
+ // Generate similar markup if this is an other error.
+ // See: <https://github.com/KaTeX/KaTeX/blob/5dc7af0/docs/error.md>.
  result = [
  {
  type: 'element',