dont send the selection back, use 200 instead

back/src/routes/selection.ts

@@ -10,7 +10,8 @@ export default function(): IRouter {
         if (!(body.selection instanceof Array)) { res.send(400); return; }
 
         req.session.selection = body.selection;
-        res.send(req.session.selection);
+        res.status(200);
+        res.send('');
         return
     });