unit

ccess": string} | {"error": string}, which is frankly a perfectly reasonable way of doing things: an untagged, but still unambiguous, union. It can make for quite pleasant code, too: `if response.success` and such. You’re looking for a tagged union, something like {"result": "success" | "error", "message": string} (or alternatively like {"result": "success", "message": string} | {"result": "error", "code": string, …}), which is also a perfectly reasonable way of doing things. In some ways it can be viewed as more principled, as it more formally allows you to check the tag. Really, the two approaches are much of a muchness. They each have their strengths and their weaknesses. But if general status is being done at the HTTP layer, I’d prefer {"message": "Reconfiguration done."}, or… well, actually, just a 204 No Content response, and no JSON or body at all. (On the terms untagged and tagged unions as I’m using them: they’re necessarily a bit different from the concepts as exposed in languages like C, since you’re dealing with a model built on objects rather than bytes, but they’re still reasonable descriptions of them. In Serde’s classifications, they’d be the untagged and internally tagged enum representations <https://serde.rs/enum-representations.html>.)