The JSON search endpoint is reliably WAF-blocked (403) for public clients, so
probing it on every call doubled request volume against Reddit's per-IP rate
limit and tripped 429 on the RSS fallback, blanking the sentiment feed. Fetch
the Atom/RSS feed directly (JSON kept as an opt-in path that still degrades to
RSS on 403), back off once on a 429 honouring Retry-After, and pace requests a
little wider. Also broaden the error handling to catch http.client chunked
transfer errors (IncompleteRead/BadStatusLine) alongside OSError, which on their
own slipped through and crashed the pipeline.