Best effort connector delete

Signed-off-by: Bryan Frimin <bryan@probo.com>

pkg/accessreview/access_source_service.go

@@ -261,11 +261,27 @@ func (s AccessSourceService) Delete(
 				return nil
 			}
 
+			// Garbage-collecting the connector is best-effort. A
+			// concurrent transaction may insert a new access source or
+			// SCIM bridge referencing this connector between the counts
+			// above and the DELETE, producing a foreign-key violation.
+			// Run the delete inside a savepoint so such a failure rolls
+			// back only the GC attempt and still commits the access
+			// source deletion instead of aborting the whole transaction.
+			if err := conn.Savepoint(
+				ctx,
+				func(ctx context.Context, conn pg.Tx) error {
 					cnnctr := &coredata.Connector{ID: *source.ConnectorID}
 					if err := cnnctr.Delete(ctx, conn, s.scope); err != nil {
 						return fmt.Errorf("cannot delete connector: %w", err)
 					}
 
+					return nil
+				},
+			); err != nil {
+				return err
+			}
+
 			return nil
 		},
 	)

pkg/coredata/connector.go

@@ -322,6 +322,12 @@ WHERE %s AND id = @id
 
 	_, err := conn.Exec(ctx, q, args)
 	if err != nil {
+		if pgErr, ok := errors.AsType[*pgconn.PgError](err); ok {
+			if pgErr.Code == "23503" {
+				return ErrResourceInUse
+			}
+		}
+
 		return fmt.Errorf("cannot delete connector: %w", err)
 	}