fix: handle missing attachments in ARF detection

Prevent TypeError when messageInfo.attachments is undefined or null
during email sync by adding fallback to empty array.

Author: andris9

lib/arf-detect.js

@@ -27,7 +27,7 @@ const arfDetect = async messageInfo => {
 
     let returnPath;
 
-    for (let attachment of messageInfo.attachments) {
+    for (let attachment of messageInfo.attachments || []) {
         switch (attachment.contentType.toLowerCase()) {
             case 'message/feedback-report': {
                 // found a feedback report

test/complaint-test.js

@@ -61,6 +61,40 @@ function mightBeAComplaint(messageInfo) {
 }
 
 test('ARF complaint detection tests', async t => {
+    await t.test('handles missing attachments gracefully', async () => {
+        // Test with undefined attachments
+        const messageInfoUndefined = {
+            from: { address: 'test@example.com' },
+            subject: 'Test'
+        };
+        const reportUndefined = await arfDetect(messageInfoUndefined);
+        assert.ok(reportUndefined);
+        assert.deepStrictEqual(reportUndefined.arf, {});
+        assert.deepStrictEqual(reportUndefined.headers, {});
+
+        // Test with null attachments
+        const messageInfoNull = {
+            from: { address: 'test@example.com' },
+            subject: 'Test',
+            attachments: null
+        };
+        const reportNull = await arfDetect(messageInfoNull);
+        assert.ok(reportNull);
+        assert.deepStrictEqual(reportNull.arf, {});
+        assert.deepStrictEqual(reportNull.headers, {});
+
+        // Test with empty attachments array
+        const messageInfoEmpty = {
+            from: { address: 'test@example.com' },
+            subject: 'Test',
+            attachments: []
+        };
+        const reportEmpty = await arfDetect(messageInfoEmpty);
+        assert.ok(reportEmpty);
+        assert.deepStrictEqual(reportEmpty.arf, {});
+        assert.deepStrictEqual(reportEmpty.headers, {});
+    });
+
     await t.test('Yahoo ARF abuse report', async () => {
         const messageInfo = await parseForArfDetect(path('yahoo.eml'));
         const report = await arfDetect(messageInfo);