add

index.html

@@ -198,7 +198,7 @@
             evt.currentTarget.className += " active";
 
             const descriptionElement = document.getElementById("taskDescription");
-            descriptionElement.innerHTML = descriptions[tabName];
+            descriptionElement.innerHTML = descriptions[tabName] || "";
             MathJax.Hub.Queue(["Typeset", MathJax.Hub, "taskDescription"]);
         }