message: limit visibility of CycleError
diff: @@ -238,7 +238,7 @@ pub type CycleParticipants = Arc<Vec<DatabaseKeyIndex>>;
  /// The error returned when a query could not be resolved due to a cycle
  #[derive(Eq, PartialEq, Clone, Debug)]
  -pub struct CycleError {
  +pub(crate) struct CycleError {
  /// The queries that were part of the cycle
  pub(crate) cycle: CycleParticipants,
  pub(crate) changed_at: Revision,
  