test: handle non-serializable tracking payloads

Author: parneetbrar234-svg

utils/tracking.test.ts

@@ -61,5 +61,21 @@ describe('trackUser', () => {
     trackUser('testuser');
 
     expect(fetchMock).toHaveBeenCalledTimes(1);
+  });
+     it('reports format error for non-serializable JSON payload', () => {
+    const consoleErrorMock = vi.spyOn(console, 'error').mockImplementation(() => {});
+    const fetchMock = vi.fn();
+    vi.stubGlobal('fetch', fetchMock);
+
+    const payload: Record<string, unknown> = {};
+    payload.self = payload;
+
+    trackUser(payload as unknown as string);
+
+    expect(consoleErrorMock).toHaveBeenCalledWith(
+      'Failed to format tracking payload',
+      expect.any(TypeError),
+    );
+    expect(fetchMock).not.toHaveBeenCalled();
   });
 });

utils/tracking.ts

@@ -1,7 +1,14 @@
 export function trackUser(username: string) {
   if (typeof navigator === 'undefined' || typeof window === 'undefined') return;
 
-  const payload = JSON.stringify({ username });
+  let payload: string;
+
+  try {
+    payload = JSON.stringify({ username });
+  } catch (error) {
+    console.error('Failed to format tracking payload', error);
+    return;
+  }
 
   const beaconQueued = navigator.sendBeacon
     ? navigator.sendBeacon('/api/track-user', new Blob([payload], { type: 'application/json' }))