Telemetry showed ~66 PropagationGridWorker exceptions per 6h with
55 ArgumentErrors and 11 TimeoutErrors, producing ~13 discarded
chain steps. Each discard broke the chain: subsequent forecast
hours were never enqueued, leaving the score store with huge gaps
(e.g. at 14:11 UTC the earliest available forecast was 18:00,
because f00-f05 all failed somewhere upstream and nothing ran
after them).
Three changes:
1. PropagationGridWorker: on the final attempt, still enqueue
fh+1 even when this step failed. Oban discards the current
job normally — but the rest of the chain keeps running, so
one bad hour doesn't take out the remaining 12-18. The
rescue is factored into a tested public helper.
2. HrrrClient.parse_idx: skip malformed idx lines instead of
raising. NOAA S3 occasionally serves an HTML error page as
the idx body, and the old strict String.to_integer path
raised ArgumentError on the first non-numeric line and took
down the chain step. This is the root cause of the 55
ArgumentErrors.
3. JS renderTimeline: when no forecast hour is at-or-before
wall-clock (all times are future — the gap scenario the
fixes above are designed to prevent), stop labeling the
earliest future slot "Now". Lets the user see honest
"+Nh" offsets instead of a lie on the pill.