Well, not completely though.
You forgot to revert the hook-change in plugin.json:
The "error throwing" part of the com-message refers to
At that point I get
ratio === undefined, yet width is also not given. Whereever this
$el comes from there, it doesn't have
Can't explain why it's not showing in your ACP list. Didn't have any problems with that.
If it were working, would you prefer that Markdown hook over the post-parse one? Regarding downward compatibility, I'm hoping that there's a way to add hook handlers in an
init function, isn't there? So you could check for Markdown and from there on set the appropriate hooks.