When a block is broken in a layout, we show a red message as the block description:

...but there is no hint whatsoever elsewhere. I would expect that red color to "propagate" back all the way forming some sort of trail that the site admin could follow. So there should be a site status error too that triggers the admin bar red badge to show:

...and then on the manage layouts page, the layout name (and perhaps the template icon too) should also be red:

  
Recent comments
Another contrib module came to my mind: Save & Edit. Of course, that's also not what you had in mind - it saves to the server. But it can be helpful when the network the author's...
Implementing autosave in Ckeditor 5
... Autosave module that you mentioned, but it saves to the database I thought, that's what you're after. I am looking for is to save to localStorage...
Implementing autosave in Ckeditor 5
Thanks for your prompt reply. I tried the Autosave module that you mentioned, but it saves to the database, and the behavior I am looking for is to save to localStorage, in other words,...
Implementing autosave in Ckeditor 5