New thread comment is lost if title is empty after Markdown is removed

[trichoplax]

If the title of a new comment thread is left blank, the beginning of the comment is used instead, with any Markdown removed. This means that if the entire comment is a quote block (for example), it will be removed leaving an empty title. This is rejected with the message:

Could not create comment thread: Title can't be empty after Markdown is removed.

Would it be possible to display this message without reloading the page, so that the typed comment is not lost and the user can manually enter a title rather than needing to enter the comment again?

[cellio]

Alternatively, instead of making the user think about a title that "should" have just defaulted to something, let's fill in a title -- if we can't use the comment content because it's been stripped away, we could use something generic like "new thread" and people can rename it.

Data loss is bad so I'm tagging this as a bug, but I'd rather intercept the error than tell the user to do extra work, if we can do something reasonable instead.

[trichoplax]

if we can't use the comment content because it's been stripped away, we could use something generic like "new thread"

This sounds better. How important is title uniqueness between threads under the same post? If this happens twice, can both threads be called "New thread" until someone renames them, or should they be something like "Thread 1" and "Thread 2"?

[cellio]

As far as I know thread titles are purely decorative and nothing in the code depends on them being unique. From a UX perspective I have no problem with duplicate titles now that people can rename as needed.