when i am registering or login it is giving error

Unexpected token '<', "<!DOCTYPE "... is not valid JSON
check this out and solve it properly

auth-api.js

@@ -103,6 +103,22 @@ router.post('/login', [
         res.status(500).json({ message: 'Server error' });
     }
 });
+// Token verification endpoint
+router.get('/verify', async (req, res) => {
+    try {
+        // Get token from header
+        const token = req.header('Authorization')?.replace('Bearer ', '');
+        if (!token) {
+            return res.json({ valid: false });
+        }
+
+        // Verify token
+        jwt.verify(token, JWT_SECRET);
+        res.json({ valid: true });
+    } catch (error) {
+        res.json({ valid: false });
+    }
+});
 
 // Protected route example
 router.get('/profile', async (req, res) => {

index.html

@@ -293,10 +293,9 @@ const settingsBtn = document.getElementById('settingsBtn');
             authError.classList.add('hidden');
             authError.textContent = '';
         }
-
         async function loginUser(email, password, username = null) {
             try {
-                const response = await fetch('/api/auth/login', {
+                const response = await fetch('https://chatrouter-api.example.com/api/auth/login', {
                     method: 'POST',
                     headers: {
                         'Content-Type': 'application/json'
@@ -308,12 +307,20 @@ const settingsBtn = document.getElementById('settingsBtn');
                     })
                 });
 
-                const data = await response.json();
-
                 if (!response.ok) {
-                    throw new Error(data.message || 'Login failed');
+                    const errorText = await response.text();
+                    try {
+                        // Try parsing as JSON first
+                        const errorData = JSON.parse(errorText);
+                        throw new Error(errorData.message || 'Login failed');
+                    } catch (e) {
+                        // If not JSON, show raw error
+                        throw new Error(errorText || 'Login failed');
+                    }
                 }
 
+                const data = await response.json();
+
                 // Store user session
                 localStorage.setItem('chatRouterUser', data.user.username);
                 localStorage.setItem('chatRouterToken', data.token);
@@ -326,12 +333,11 @@ const settingsBtn = document.getElementById('settingsBtn');
                 authModal.classList.add('hidden');
                 
             } catch (error) {
-                authError.textContent = error.message;
+                authError.textContent = error.message.replace('Error: ', '').replace('error: ', '');
                 authError.classList.remove('hidden');
             }
         }
-
-        async function registerUser(username, email, password) {
+async function registerUser(username, email, password) {
             try {
                 const response = await fetch('/api/auth/register', {
                     method: 'POST',
@@ -375,17 +381,29 @@ const settingsBtn = document.getElementById('settingsBtn');
             updateAuthUI();
             addMessage('system', 'Please log in to start chatting.');
         }
-
-        function checkAuthStatus() {
+        async function checkAuthStatus() {
             const token = localStorage.getItem('chatRouterToken');
             if (!token) return false;
 
-            // Here you would verify the token with the backend
-            // For now we'll just check if it exists
-            return true;
-        }
+            try {
+                const response = await fetch('https://chatrouter-api.example.com/api/auth/verify', {
+                    method: 'GET',
+                    headers: {
+                        'Authorization': `Bearer ${token}`
+                    }
+                });
 
-        // Chat management
+                if (response.ok) {
+                    const data = await response.json();
+                    return data.valid;
+                }
+                return false;
+            } catch (error) {
+                console.error('Auth verification failed:', error);
+                return false;
+            }
+        }
+// Chat management
         let currentChatId = null;
 
         function generateChatId() {