Casting EntityRef to Entity supports nullable

src/gaemstone/ECS/EntityRef.cs

@@ -59,7 +59,8 @@ public unsafe sealed class EntityRef
 		{ if (path?.IsAbsolute == true) throw new ArgumentException("path must not be absolute", nameof(path)); return path; }
 
 
-	public EntityRef? Parent => GetTarget(Universe.ChildOf);
+	public EntityRef? Parent
+		=> GetTarget(Universe.ChildOf);
 
 	public IEnumerable<EntityRef> GetChildren()
 	{
@@ -163,9 +164,9 @@ public unsafe sealed class EntityRef
 	public static IdentifierRef operator &(EntityRef relation, Entity target) => IdentifierRef.Pair(relation, target);
 	public static IdentifierRef operator &(Entity relation, EntityRef target) => IdentifierRef.Pair(relation, target);
 
-	public static implicit operator Entity(EntityRef e) => e.Entity;
-	public static implicit operator ecs_entity_t(EntityRef e) => e.Entity.Value;
+	public static implicit operator Entity(EntityRef? e) => e?.Entity ?? default;
+	public static implicit operator ecs_entity_t(EntityRef? e) => e?.Entity.Value ?? default;
 
-	public static implicit operator Identifier(EntityRef e) => new(e.Entity.Value.Data);
-	public static implicit operator ecs_id_t(EntityRef e) => e.Entity.Value.Data;
+	public static implicit operator Identifier(EntityRef? e) => new(e?.Entity.Value.Data ?? default);
+	public static implicit operator ecs_id_t(EntityRef? e) => e?.Entity.Value.Data ?? default;
 }