A scan drainer and the background MatchWorker can process the same folder
concurrently. When a provider-ID merge moves a series' episodes to the survivor
and deletes the source, an in-flight ensureSeriesEpisodeLinks(sourceID) hits
catalog.ErrItemNotFound and was failing the whole scan. The episodes are already
reattached, so this is benign: log and continue (matching the lenient call sites)
instead of failing. Genuine errors still abort.
Silo Server Developer
aab0a804b9