ServerResponse

"Error" subclass representing a >=400 response from the server.

Whether or not this is an error depends on your application.

The json field can be undefined if the server responded with an empty response body. This shouldn't generally happen. Most "bad" responses come with a JSON error description, or (if they're fronted by a CDN or nginx or something) occasionally non-JSON responses (which become UnparseableResponseErrors, above).