Codemirror fails a lot so I've turned it off

**Describe the bug**

Codemirror keeps choking on some aspect of markup. It's not obvious to me what is making it so unhappy. The problem is it fails the entire page so all subsequent code blocks are unreadable.

I can't identify what Codemirror is doing over contenteditable code blocks at the moment as it has no other interactive properties.

So for now I've turned it off. But it would be good to fix and extend it at some point!

**What is wrong with this content?**

**How could this be fixed?**

**Link to content**

**Additional context**

**Who else might need to know about this?**