Fix: Prevent division by zero in progress calculations (#265)

Author: joe-replin

js/PageLevelProgressIndicatorView.js

@@ -57,7 +57,8 @@ class PageLevelProgressIndicatorView extends Backbone.View {
     if (isPresentationComponentWithItems) {
       const children = this.model.getChildren();
       const visited = children.filter(child => child.get('_isVisited'));
-      return Math.round(visited.length / children.length * 100);
+      // Handle division by zero when component has no children
+      return children.length === 0 ? 0 : Math.round(visited.length / children.length * 100);
     }
     return 0;
   }

js/completionCalculations.js

@@ -132,7 +132,8 @@ class Completion extends Backbone.Controller {
     // this allows the user to see if assessments have been passed, if assessment components can be retaken, and all other component's completion
     const completed = completionObject.nonAssessmentCompleted + completionObject.assessmentCompleted + completionObject.subProgressCompleted;
     const total = completionObject.nonAssessmentTotal + completionObject.assessmentTotal + completionObject.subProgressTotal;
-    const percentageComplete = Math.floor((completed / total) * 100);
+    // Handle division by zero when page contains only optional content
+    const percentageComplete = total === 0 ? 0 : Math.floor((completed / total) * 100);
     return percentageComplete;
   }