Don't register sparse sets for relations.

Author: OptimisticPeach

crates/bevy_ecs/src/storage/sparse_set.rs

@@ -391,6 +391,8 @@ impl SparseSets {
         self.relation_sets.get(relation_kind)
     }
 
+    // FIXME(Relationships): https://discord.com/channels/691052431525675048/749335865876021248/862199702825205760
+    // FIXME(Relationships): Deal with the ability to register components with a target, and relations without one
     pub fn get_or_insert(
         &mut self,
         relation_kind: &RelationKindInfo,

crates/bevy_ecs/src/world/mod.rs

@@ -190,15 +190,7 @@ impl World {
         &mut self,
         descriptor: ComponentDescriptor,
     ) -> Result<RelationKindId, RelationsError> {
-        let storage_type = descriptor.storage_type();
-        let relation_kind = self.components.new_relationship_kind(descriptor)?;
-
-        // ensure sparse set is created for SparseSet components
-        if storage_type == StorageType::SparseSet {
-            self.storages.sparse_sets.get_or_insert(relation_kind, None);
-        }
-
-        Ok(relation_kind.id())
+        Ok(self.components.new_relationship_kind(descriptor)?.id())
     }
 
     /// Retrieves an [EntityRef] that exposes read-only operations for the given `entity`.