Linking to quotes of deleted post causes error state which blocks posting

[scottdotweb]

Steps to Reproduce

I've only confirmed this on desktop so far (browser: Firefox Developer Edition on Windows).

It's impossible to post the URL of quotes view of a post which has been deleted, because the app tries to retrieve the post, fails, and sets an error state. That error state is then impossible to remove from the post composer.

To reproduce:

1. Post
2. Quote that post
3. Get the quotes view URL for the original post (.../post/abcdefghijkl123/quotes)
4. Delete the original post
5. Try to post the URL of the quotes view.

The composer will display this error:

 

6. Dismiss the error message and clear the composer
7. Try to post something else.

The same error will be shown and posting prevented:

 
When this happens, the only way to post is to close and reopen the composer.