Update static/frontend.js

static/frontend.js

@@ -70,7 +70,15 @@
         return predictions.json()
       } else{
         document.getElementById("spinner").style.display = 'none';
-        let error_msg = "Error, return code" + predictions.status
+        let error_msg = ''
+        if (predictions.status == 999) {
+          error_msg = "Library not found"
+        }
+        else if (predictions.status == 504) {
+          error_msg = "Timeout!"
+        } else {
+          error_msg = "Error, return code: " + predictions.status
+        }
         alert(error_msg);
       }