Fix small bug in diet.js (add "let" in "for-of-loop").

frontend/www/scripts/diet.js

@@ -152,7 +152,7 @@ async function retrieveDiet(id) {
         // adding mealtype instances
         let mealtypeInstances = [];
         let mealtypeInstancesTypes = formData.getAll("type");
-        for (value of mealtypeInstancesTypes) {
+        for (let value of mealtypeInstancesTypes) {
             mealtypeInstances.push({
                 mealtype: `${HOST}/api/mealtypes/${value}/`,
             });