req-error.md
In httr2: Perform HTTP Requests and Process the Responses

failing callback still generates useful body

Failed to parse error body with method defined in `req_error()`.
Caused by error:
! This is an error!

Code
  req <- request_test("/status/404")
  req <- req %>% req_error(body = ~ resp_body_json(.x)$error)
  req %>% req_perform()
Condition
  Error in `req_perform()`:
  ! Failed to parse error body with method defined in `req_error()`.
  Caused by error in `resp_body_json()`:
  ! Unexpected content type "text/plain".
  * Expecting type "application/json" or suffix "json".