Capturing from GitHub creates a bookmark instead of a markdown and the bookmark crashes the app

I tested this successfully but it’s unclear what your web archive actually contains. Did you clip the raw Markdown file or just its rendering?

I clipped the Github page rendering the Markdown file. For example: https://github.com/mpco/AlfredWorkflow-DEVONthink-Search/blob/master/README.md

The script was intended for a web archive containing the raw Markdown file.

Point taken. Unfortunately, the resulting Markdown is not really rendered as Markdown in DT.

There’s also the Convert –> to Markdown built-in action, which does a reasonable (though, also, not perfect) job.

However, regardless of how the Markdown document is produced from the Web Archive, I would have to implement an Update Captured Markdown script to do what the built-in Update Captured Archive action does.

It’s definitely worth exploring further (when time permits)…