Fix deferred MongoDB read exception translation

Changelog.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Translate MongoDB driver failures from all nine lazy synchronous reads at cursor acquisition and subsequent batches, preserving streaming, cursor disposal, and serializer exception identity. Async reads, public signatures, stored data, CI, and the MongoDB 4.2 minimum are unchanged. [#91](https://github.com/NEventStore/NEventStore.Persistence.MongoDB/issues/91)
+
 - Make exact-ID explain assertions accept MongoDB IDHACK as well as named index plans, while verifying the built-in index, bounded examined work and absence of collection scans. Add plan-layout regression coverage and a forced-scan negative control. Test-only change; no API, schema or MongoDB minimum-version change and no migration required. [#94](https://github.com/NEventStore/NEventStore.Persistence.MongoDB/issues/94)
 
 - Atomically advance snapshot metadata without losing concurrent or delayed commit increments. Older snapshots cannot regress the recorded snapshot revision. Preserve configured write concerns; legacy heads without an unsnapshotted counter use the current head-minus-snapshot value as a fallback. Existing incorrect counters are not repaired. [#90](https://github.com/NEventStore/NEventStore.Persistence.MongoDB/issues/90)
@@ -22,6 +24,10 @@
 
 ### Breaking Changes
 
+- Synchronous reads reuse one cursor `MoveNext` callback per enumeration. Both protected virtual `TryMongo` overloads are still called for cursor acquisition and every batch attempt, including completion. Source and binary APIs are unchanged, but overrides that inspect callback reference identity now observe the same callback within an enumeration. [#91](https://github.com/NEventStore/NEventStore.Persistence.MongoDB/issues/91)
+
+- Synchronous enumeration now reports driver failures as `StorageException` or `StorageUnavailableException` (for `MongoConnectionException`), rather than leaking raw driver exceptions. Consumers that caught driver exceptions from iteration must handle the persistence exceptions instead. Keep the persistence engine alive until enumeration finishes; deferred driver calls now enforce its existing disposed-engine guard. Serializer errors remain unchanged. [#91](https://github.com/NEventStore/NEventStore.Persistence.MongoDB/issues/91)
+
 - **MongoDB 4.2 or later is now required** for aggregation-based snapshot metadata updates. Upgrade MongoDB before upgrading this adapter. No stored-schema migration is needed; MongoDB 4.2 is the feature minimum, not a recommended production release. This change does not repair historical metadata or solve stream lifecycle races. [#90](https://github.com/NEventStore/NEventStore.Persistence.MongoDB/issues/90)
 
 - New recycled records use the synthetic stored `StreamId`. Older adapter binaries expose that value and cannot find these records by the original stream ID; raw readers that assume stored `StreamId` is original see the same change. Upgrade recycle-bin readers before deleting streams with the new format. Existing recycled records need no backfill. [#87](https://github.com/NEventStore/NEventStore.Persistence.MongoDB/issues/87)