Fix "featureless" structure property quizzing

static/anatomy-quiz.html

@@ -107,17 +107,21 @@
 
       quiz_list.push(`id: ${structure}`);
 
+      let questions = [];
       if ("features" in props) {
         for (feature in props["features"]) {
-          let questions = feature_question(
+          questions = feature_question(
             `${feature} of ${structure}`,
             props["features"][feature]
           );
+        }
+      } else {
+        questions = feature_question(structure, props);
+      }
+
       for (const question of questions) {
         quiz_list.push(question);
       }
-        }
-      }
 
       return quiz_list;
     }