Reliable/reproducible error in a 'hello world' example using @codemirror/lang-html when typing the final character to close a <script> tag in certain situations.

[josephrocca]

Describe the issue

In the reproduction link below, try typing > at the end of the first line to close the script tag. In the browser console you should see this error:

Uncaught TypeError: Cannot read properties of undefined (reading 'to')
    at Parse.moveRangeIndex (@codemirror-language.js:2392:45)
    at new Parse (@codemirror-language.js:2329:14)
    at Parser.createParse (@codemirror-language.js:2206:24)
    at Parser.startParse (@lezer-common.js:1730:21)
    at MixedParse.startInner (@lezer-common.js:1891:97)
    at MixedParse.advance (@lezer-common.js:1810:18)
    at @codemirror-language.js:363:39
    at ParseContext.withContext (@codemirror-language.js:398:20)
    at ParseContext.work (@codemirror-language.js:351:21)
    at LanguageState.apply (@codemirror-language.js:537:20)

But notice that if you delete everything from the text editor except <script></script and then try typing the final >, then it works fine.

So I guess it has something to do with the transition of the 'content' of the script tag (i.e. everything after <script>) during the transition from it no longer being considered part of the script tag, since the script tag was (about to be) closed at a position before it in the document.

Thanks!

Browser and platform

Chrome, Ubuntu 22.04

Reproduction link

https://codemirror.net/try/?c=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

[marijnh]

This patch should help.

[josephrocca]

That solved it, thank you! 🙏

[josephrocca]

Hey @marijnh looks like there might be an unhandled edge case. I tried my hardest to trim this down (from 3k+ lines), but the bug was really sensitive to removing random bits, so after about 30 minutes, this is what I got it down to:

• https://codemirror.net/try bug reproduction link (Edit: Ah, link too big for your server [maybe store in hash if it's too big for url params?] so here's a gist: https://gist.github.com/josephrocca/1bc2fb2ae5a4c558f5b602963815932b )

If you scroll down to the bottom and try adding the final > to the end of <script></script> it'll throw the same error as before, and not let you type:

(Goes without saying, but this will produce invalid code, since </script> will close the parent <script> tag, but of course this should just 'break' the syntax highlighting, and not the editor itself.)

[marijnh]

Thanks for reproducing that. Attached patch should cover this case.

(I've updated the /try system to use URL fragments, not query parameters, to allow bigger scripts to be linked.)

[josephrocca]

Thank you! 🙏