Index: backend/models/Challenge.js
===================================================================
--- backend/models/Challenge.js	(revision 745232a4ac626272f4a8c53cf347c9bce8605547)
+++ backend/models/Challenge.js	(revision 91d4df204a816c5b48529e0fb589c7a339fd2abe)
@@ -2,6 +2,6 @@
   constructor(data = {}) {
     this.id = data.id;
-    this.title = data.title || '';
-    this.content = data.content || '';
+    this.title = data.title || "";
+    this.content = data.content || "";
     this.solving_date = data.solving_date;
     this.attempted_by = data.attempted_by;