I've encountered two small but potentially breaking issues when working with Categories via REST.
Attempting to add a category by POSTing /api/v2/nodes/{id}/categories/ to a node that already has the specified category applied returns a 500. The posted documentation for all versions of the API state that it should be returned as a 400.
Also, there is a small typo between the documented reason text and the error value that is actually being returned - insignificant yes, but enough to break an .endsWith() string evaluation. This is also present the API documentation for all versions.
I haven't had the best success in the past working with the customer support team to report this type of issue. Is there a better venue since the latest overhaul of the Developer ecosystem, or do I need to go irritate those poor people again?