Improve error handling for menu data fetching and update HTML structure: Enhance error logging in menuDataController, provide user-friendly error messages, and streamline the index.html file by adding new script references while removing an unused image.

utils/fetchMenuData.js

@@ -1,24 +1,22 @@
 const { MenuItem } = require('../models');
+const { withDbRetries } = require('./withDbRetries');
 
 async function fetchMenuData() {
-  try {
-    const menuItems = await MenuItem.findAll({
-      order: [['order_id', 'ASC']],
-      include: [{
-        model: MenuItem,
-        as: 'submenu',
-        required: false,
-        order: [['order_id', 'ASC']]
-      }]
-    });
-
-    const menuData = buildMenuStructure(menuItems);
-
-    return menuData;
-  } catch (error) {
-    console.error('There was a problem fetching the menu data:', error);
-    return [];
-  }
+  return withDbRetries(
+    async () => {
+      const menuItems = await MenuItem.findAll({
+        order: [['order_id', 'ASC']],
+        include: [{
+          model: MenuItem,
+          as: 'submenu',
+          required: false,
+          order: [['order_id', 'ASC']]
+        }]
+      });
+      return buildMenuStructure(menuItems);
+    },
+    { attempts: 3, baseDelayMs: 200 }
+  );
 }
 
 function buildMenuStructure(menuItems) {

utils/withDbRetries.js

@@ -0,0 +1,51 @@
+const sequelize = require('../config/database');
+
+const DEFAULTS = {
+  attempts: 3,
+  baseDelayMs: 200,
+};
+
+function delay(ms) {
+  return new Promise((resolve) => setTimeout(resolve, ms));
+}
+
+/**
+ * Führt eine DB-Operation bis zu `attempts` mal aus. Nach einem Fehler:
+ * kurzes Backoff, dann Verbindung mit authenticate() neu prüfen (frische
+ * Verbindung aus dem Pool), erneuter Versuch.
+ * Kein sequelize.close() — würde die gemeinsame Instanz für alle Requests killen.
+ */
+async function withDbRetries(operation, options = {}) {
+  const { attempts, baseDelayMs } = { ...DEFAULTS, ...options };
+  let lastError;
+
+  for (let attempt = 1; attempt <= attempts; attempt++) {
+    try {
+      if (attempt > 1) {
+        const backoff = baseDelayMs * 2 ** (attempt - 2);
+        await delay(backoff);
+        try {
+          await sequelize.authenticate();
+        } catch (authErr) {
+          console.warn(
+            `DB authenticate vor Wiederholung ${attempt}/${attempts} fehlgeschlagen:`,
+            authErr.message
+          );
+        }
+      }
+      return await operation();
+    } catch (error) {
+      lastError = error;
+      console.error(
+        `DB-Operation Versuch ${attempt}/${attempts} fehlgeschlagen:`,
+        error.message
+      );
+      if (attempt === attempts) {
+        throw error;
+      }
+    }
+  }
+  throw lastError;
+}
+
+module.exports = { withDbRetries };