- 🇳🇿New Zealand quietone
The last comment confirms that this is no longer a problem. The only confirmed report of this is from a contrib module.
Therefor, closing.
For anoyone who might still reach this from search results:
Incorrectly configured paths (for example, from custom resources) also give an empty messages. For example, if the path "/custom_resource/{entity}" cannot receive an "entity" parameter (because, say, it expects a "custom_entity" one).
Although, in my opinion, this also falls within the scope of this issue since custom resources are by definition extending the core rest infrastructure, and so it should therefore be reopened (or a new one created).