Lazy loading fixes (#2362)

* Return some more usefully wrapped errors when doing sync

* Remove unnecessary error check

* Couple of guards around `sql.ErrNoRows`

* Nolint

1 files changed, 9 insertions, 7 deletions

diff --git a/syncapi/streams/stream_pdu.go b/syncapi/streams/stream_pdu.go
index ddc2f55c..0f11d55f 100644
--- a/syncapi/streams/stream_pdu.go
+++ b/syncapi/streams/stream_pdu.go
@@ -3,6 +3,7 @@ package streams
 import (
 	"context"
 	"database/sql"
+	"fmt"
 	"sync"
 	"time"
 
@@ -205,6 +206,7 @@ func (p *PDUStreamProvider) IncrementalSync(
 	return newPos
 }
 
+// nolint:gocyclo
 func (p *PDUStreamProvider) addRoomDeltaToResponse(
 	ctx context.Context,
 	device *userapi.Device,
@@ -228,13 +230,16 @@ func (p *PDUStreamProvider) addRoomDeltaToResponse(
 		eventFilter, true, true,
 	)
 	if err != nil {
-		return r.From, err
+		if err == sql.ErrNoRows {
+			return r.To, nil
+		}
+		return r.From, fmt.Errorf("p.DB.RecentEvents: %w", err)
 	}
 	recentEvents := p.DB.StreamEventsToEvents(device, recentStreamEvents)
 	delta.StateEvents = removeDuplicates(delta.StateEvents, recentEvents) // roll back
 	prevBatch, err := p.DB.GetBackwardTopologyPos(ctx, recentStreamEvents)
 	if err != nil {
-		return r.From, err
+		return r.From, fmt.Errorf("p.DB.GetBackwardTopologyPos: %w", err)
 	}
 
 	// If we didn't return any events at all then don't bother doing anything else.
@@ -268,15 +273,12 @@ func (p *PDUStreamProvider) addRoomDeltaToResponse(
 	}
 
 	if stateFilter.LazyLoadMembers {
-		if err != nil {
-			return r.From, err
-		}
 		delta.StateEvents, err = p.lazyLoadMembers(
 			ctx, delta.RoomID, true, limited, stateFilter.IncludeRedundantMembers,
 			device, recentEvents, delta.StateEvents,
 		)
-		if err != nil {
-			return r.From, err
+		if err != nil && err != sql.ErrNoRows {
+			return r.From, fmt.Errorf("p.lazyLoadMembers: %w", err)
 		}
 	}