Fix internal error in api/pinned-users if one or more name fails to resolve

packages/backend/src/server/api/endpoints/pinned-users.ts

@@ -45,7 +45,7 @@ export default define(meta, paramDef, async (ps, me) => {
 	);
 
 	return await Users.packMany(
-		users.filter((x) => x !== undefined) as User[],
+		users.filter((x) => (x != null)) as User[],
 		me,
 		{ detail: true },
 	);