Fix EventPage.CalculateCeiling crash on fully-skipped batch (marten#4663)#416
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…page When error handling is configured to skip events and every event in a full batch is skipped, the EventPage is empty (Count == 0) while Count + skippedEvents == batchSize. CalculateCeiling then called Last() on the empty page and threw "Sequence contains no elements", crashing projection rebuilds. Guard the Last() access with Count > 0 and fall back to the high water mark so the daemon keeps making progress. Fixes JasperFx/marten#4663 Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Problem
EventPage.CalculateCeilingcallsthis.Last().Sequencewhenever(Count + skippedEvents) == batchSize. When error handling is configured to skip events (serialization/application/unknown event errors) and every event in a full batch is skipped, the page is empty (Count == 0) whileCount + skippedEvents == batchSize.Last()then throwsSystem.InvalidOperationException: Sequence contains no elements, crashing projection rebuilds.Reported in JasperFx/marten#4663 (Marten v8.37.2, small batch sizes, event skipping, optimized rebuilds, HotCold daemon).
Fix
Guard the
Last()access with&& Count > 0. When the page is entirely skipped events, fall back to the high water mark so the daemon keeps making progress instead of throwing.Tests
Added
EventPageTestscovering the full-page, not-full-page, and fully-skipped-batch (regression) cases. All pass on net9.0 and net10.0.Fixes JasperFx/marten#4663
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