- Rename shadowed `max_retries` variable to `llm_max_retries` and move
config resolution outside the loop; the old code captured `range(2)`
then overwrote `max_retries` inside the loop, so comparisons used a
different value than the loop bound — causing `continue` on the final
iteration, exhausting the loop, and reaching `raise last_error` where
`last_error` was still None → TypeError
- Add fallback `raise RuntimeError(...)` after the retry loop so that if
`last_error` is None a descriptive error is raised instead of None
- Add unit tests covering non-dict JSON responses with various retry counts
