Merge branch 'develop' of https://github.com/syuilo/misskey into develop

src/server/api/endpoints/admin/moderators/add.ts

@@ -32,6 +32,10 @@ export default define(meta, async (ps) => {
 		throw new Error('user not found');
 	}
 
+	if (user.isAdmin) {
+		throw new Error('cannot mark as moderator if admin user');
+	}
+
 	await Users.update(user.id, {
 		isModerator: true
 	});