In the publishing workflow the only error that is handled meaningfully is the request for CAPTCHA. Other errors, for example abuse filter, are just silently skipped. The user will often just see a "Publishing error" without further useful debugging information. It may even happen that the article would be indicated as published even if the page was not actually created (see T87510 for an example).
To reproduce, define an abuse filter that filters all Russian letters ([а-я]), and try to type and publish something in Russian.
An error must not be silently skipped. It must at least be logged to the console and to EventLogging, and the user must not see that an article was published if it wasn't actually published.