The editor improvements are fantastic, and it removed so much code 
Unfortunately, after saving the edit, the post is no longer showing up, as the markdown isn’t quite right. It looks like the string parsing is not correct.
The top image markdown is the uneditted file. After editing you can see that the component is getting confused from the
(1) in the filename and putting that into the upload path, look at (1upload. Now that themes can have JS tests, lets add a test for the file name parsing.
I am going to disable the theme component here on Meta for a bit while this gets fixed. It’s already marked as #theme:broken-theme so nothing new here 