Early-return empty campaign source merge

Delete scoped snapshots in one statement when the desired source
set is empty; validate and merge only when IDs are present.

Signed-off-by: Cursor Agent <cursoragent@cursor.com>

Co-authored-by: Bryan FRIMIN <bryan@frimin.fr>

pkg/coredata/access_review_campaign_source.go

@@ -161,7 +161,30 @@ func (sources *AccessReviewCampaignSources) MergeByCampaignID(
 ) error {
 	uniqueSourceIDs := uniqueGIDs(accessReviewSourceIDs)
 
-	if len(uniqueSourceIDs) > 0 {
+	if len(uniqueSourceIDs) == 0 {
+		q := `
+DELETE FROM access_review_campaign_sources
+WHERE
+	%s
+	AND access_review_campaign_id = @access_review_campaign_id
+`
+		q = fmt.Sprintf(q, scope.SQLFragment())
+
+		args := pgx.StrictNamedArgs{"access_review_campaign_id": campaignID}
+		maps.Copy(args, scope.SQLArguments())
+
+		if _, err := conn.Exec(ctx, q, args); err != nil {
+			return fmt.Errorf("cannot delete campaign sources: %w", err)
+		}
+
+		return nil
+	}
+
+	sourceIDStrings := make([]string, len(uniqueSourceIDs))
+	for i, id := range uniqueSourceIDs {
+		sourceIDStrings[i] = id.String()
+	}
+
 	countQ := `
 SELECT COUNT(DISTINCT id)
 FROM access_review_sources
@@ -171,11 +194,6 @@ WHERE
 `
 	countQ = fmt.Sprintf(countQ, scope.SQLFragment())
 
-		sourceIDStrings := make([]string, len(uniqueSourceIDs))
-		for i, id := range uniqueSourceIDs {
-			sourceIDStrings[i] = id.String()
-		}
-
 	countArgs := pgx.StrictNamedArgs{"access_review_source_ids": sourceIDStrings}
 	maps.Copy(countArgs, scope.SQLArguments())
 
@@ -187,12 +205,6 @@ WHERE
 	if found != len(uniqueSourceIDs) {
 		return ErrResourceNotFound
 	}
-	}
-
-	sourceIDStrings := make([]string, len(uniqueSourceIDs))
-	for i, id := range uniqueSourceIDs {
-		sourceIDStrings[i] = id.String()
-	}
 
 	now := time.Now()