Improve error handling in server and client

public/script.js

@@ -4,7 +4,7 @@ function togglePassword() {
     passInput.setAttribute('type', type);
 }
 
-document.getElementById('smtpForm').addEventListener('submit', async function(e) {
+document.getElementById('smtpForm').addEventListener('submit', async function (e) {
     e.preventDefault();
 
     const btn = document.getElementById('testBtn');
@@ -37,6 +37,17 @@ document.getElementById('smtpForm').addEventListener('submit', async function(e)
             },
             body: JSON.stringify(data),
         });
+        if (!response.ok) {
+            // Handle non-200 responses
+            const contentType = response.headers.get("content-type");
+            if (contentType && contentType.includes("application/json")) {
+                const errorResult = await response.json();
+                throw new Error(errorResult.message || errorResult.error || "Server Error");
+            } else {
+                const text = await response.text();
+                throw new Error(`Server returned ${response.status}: ${text.substring(0, 100)}...`);
+            }
+        }
 
         const result = await response.json();
 
@@ -48,6 +59,7 @@ document.getElementById('smtpForm').addEventListener('submit', async function(e)
             statusDiv.textContent = '✅ Success! Email Sent Successfully.';
             logOutput.textContent = JSON.stringify(result.details, null, 2);
         } else {
+            // This block handles cases where response was 200 OK but success is false (business logic error)
             statusDiv.classList.add('status-error');
             statusDiv.textContent = '❌ Error: ' + result.message;
             logOutput.textContent = result.error || 'Unknown error occurred.';
@@ -56,8 +68,8 @@ document.getElementById('smtpForm').addEventListener('submit', async function(e)
     } catch (error) {
         resultsDiv.classList.remove('hidden');
         statusDiv.classList.add('status-error');
-        statusDiv.textContent = '❌ Network Error';
-        logOutput.textContent = error.toString();
+        statusDiv.textContent = '❌ Error Caught'; // Changed from "Network Error" to be more accurate
+        logOutput.textContent = error.message; // Use error.message instead of error.toString()
     } finally {
         // Reset Button
         btn.disabled = false;
@@ -67,7 +79,7 @@ document.getElementById('smtpForm').addEventListener('submit', async function(e)
 });
 
 // Auto Discovery Test Handler
-document.getElementById('autoTestBtn').addEventListener('click', async function() {
+document.getElementById('autoTestBtn').addEventListener('click', async function () {
     const btn = document.getElementById('autoTestBtn');
     const spinner = btn.querySelector('.loading-spinner');
     const btnText = btn.querySelector('.btn-text');
@@ -108,6 +120,16 @@ document.getElementById('autoTestBtn').addEventListener('click', async function(
             },
             body: JSON.stringify(autoTestData),
         });
+        if (!response.ok) {
+            const contentType = response.headers.get("content-type");
+            if (contentType && contentType.includes("application/json")) {
+                const errorResult = await response.json();
+                throw new Error(errorResult.message || errorResult.error || "Server Error");
+            } else {
+                const text = await response.text();
+                throw new Error(`Server returned ${response.status}: ${text.substring(0, 100)}...`);
+            }
+        }
 
         const result = await response.json();
 
@@ -149,8 +171,8 @@ document.getElementById('autoTestBtn').addEventListener('click', async function(
     } catch (error) {
         resultsDiv.classList.remove('hidden');
         statusDiv.classList.add('status-error');
-        statusDiv.textContent = '❌ Network Error';
-        logOutput.textContent = error.toString();
+        statusDiv.textContent = '❌ Error Caught';
+        logOutput.textContent = error.message;
     } finally {
         // Reset Button
         btn.disabled = false;

server.js

@@ -23,8 +23,7 @@ app.post('/api/test-smtp', async (req, res) => {
 
     // Log intent
     console.log(
-    `Attempting SMTP connection to ${host}:${port} (${
-      secure ? "Secure" : "Insecure"
+        `Attempting SMTP connection to ${host}:${port} (${secure ? "Secure" : "Insecure"
         }) for ${user}`
     );
 
@@ -46,9 +45,9 @@ app.post('/api/test-smtp', async (req, res) => {
         };
     }
 
+    try {
         const transporter = nodemailer.createTransport(transporterConfig);
 
-  try {
         // 1. Verify Connection
         await transporter.verify();
         console.log("SMTP Connection Verified Successfully");
@@ -248,9 +247,9 @@ app.post('/api/auto-test-smtp', async (req, res) => {
             };
         }
 
+        try {
             const transporter = nodemailer.createTransport(transporterConfig);
 
-    try {
             // Verify connection
             await transporter.verify();
             console.log(`✅ ${config.name} - Connection successful!`);
@@ -420,6 +419,16 @@ app.post('/api/auto-test-smtp', async (req, res) => {
     });
 });
 
+// Global Error Handler
+app.use((err, req, res, next) => {
+    console.error("Unhandled Error:", err);
+    res.status(500).json({
+        success: false,
+        message: "Internal Server Error",
+        error: err.message || "Unknown error occurred"
+    });
+});
+
 app.listen(port, () => {
     console.log(`Server running at http://localhost:${port}`);
 });