Last update was T176685: Update CodeMirror extension to CodeMirror library 5.30 in 2017. The currently used version is 5.35.0. Changelog since then: https://codemirror.net/doc/releases.html. As far as I can see no incompatible changes have been made, but tons of bugfixes and some performance improvements.
Note there is a version 6 update planned as well (see T259059), but this will not happen soon.
- Ping @MusikAnimal if this is ok.
- Check if the copy in the extension does not have any modifications. We don't want to loose these without knowing.
- Check the release notes again for changes that might turn out to be problematic.
- Check what tests exist in the extension's codebase.
- Replace the file in the extension.
- Locally test if it still works.