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

has useful default (with message)

Code
  req <- req_retry(req)
Message
  Setting `max_tries = 2`.

useful message if `after` wrong

Code
  req_perform(req)
Condition
  Error in `req_perform()`:
  ! The `after` callback to `req_retry()` must return a single number or NA, not a <httr2_response> object.

validates its inputs

Code
  req_retry(req, max_tries = 0)
Condition
  Error in `req_retry()`:
  ! `max_tries` must be a whole number larger than or equal to 1 or `NULL`, not the number 0.
Code
  req_retry(req, max_tries = 2, max_seconds = "x")
Condition
  Error in `req_retry()`:
  ! `max_seconds` must be a whole number or `NULL`, not the string "x".
Code
  req_retry(req, max_tries = 2, retry_on_failure = "x")
Condition
  Error in `req_retry()`:
  ! `retry_on_failure` must be `TRUE` or `FALSE`, not the string "x".