bool True, if a singleton is found to match exactly once with the specified typeEntityQuery.
Checks whether a singleton component of the specified type exists. Note that if querying a singleton component from a system-associated entity, the query must include either EntityQueryOptions.IncludeSystems or the SystemInstance component.
This method matches only the entities that this query matches, so the query's EntityQueryOptions determine whether a singleton entity is found. Unless the query uses EntityQueryOptions.IncludeDisabledEntities or EntityQueryOptions.IncludePrefab, entities that have the Disabled component or the Prefab component are excluded, and this method returns false for a singleton on one of those entities.