Silent bug in one unprotected line caused profitable Apify actor to fail repeatedly

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A developer discovered that their most profitable Apify actor — which monitors CBOE options data for unusual trading volumes — had been silently failing on a significant share of client-triggered runs. The root cause was a single unprotected line at the very end of the script: a data-push call with no error handling, meaning one malformed row could cause the entire run to fail silently. The problem went undetected for some time because Apify does not expose client run logs to actor owners, leaving only an abnormal success-rate metric as a clue. The fix involved wrapping the batch push in a fallback that retries row by row on failure, dropping only bad rows rather than discarding the full result set. A last-resort email alert was also added to notify the developer immediately if any future end-to-end run failure occurs.

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