Fix AJAX exercise JavaScript error

The error is now fixed and the Submit button is no longer
disabled after submission.

Fixes #1456

Author: ihalaij1

exercise/static/exercise/chapter.js

@@ -268,6 +268,9 @@
             $.ajax(exercise.url, {dataType: "html"})
               .done(function(data) {
                 exercise.updateSummary($(data));
+                exercise.dom_element.dispatchEvent(
+                  new CustomEvent("aplus:submission-finished",
+                    {bubbles: true, detail: {type: exercise.exercise_type}}));
               });
           }
         });
@@ -869,6 +872,7 @@
     },
 
     fillFormInputs: function(submissionData, container) {
+      if (!submissionData) return;
       submissionData.forEach(function([fieldName, fieldValue]) {
         const field = container.find('[name="' + fieldName + '"]');
         if (field.length === 0) return;

exercise/templates/exercise/exercise.html

@@ -96,9 +96,11 @@
 		$("#submit-progress").addClass("d-none");
 		var $stats = $("#exercise-info"),
 			url = $stats.data("url");
-		$stats.load(url, function() {
-			$stats.find('[data-bs-toggle="tooltip"]').tooltip();
-		});
+		if (url) {
+			$stats.load(url, function() {
+				$stats.find('[data-bs-toggle="tooltip"]').tooltip();
+			});
+		}
 	}
 });
 </script>