fix: improve error handling for session auth check

backend/src/index.ts

@@ -71,14 +71,16 @@ const app = new Elysia()
   .use(taskRoutes)
   .get("/health", () => ({ status: "ok", service: "hammer-queue" }))
   .onError(({ error, set }) => {
-    if (error.message === "Unauthorized") {
+    const msg = error?.message || String(error);
+    if (msg === "Unauthorized") {
       set.status = 401;
       return { error: "Unauthorized" };
     }
-    if (error.message === "Task not found") {
+    if (msg === "Task not found") {
       set.status = 404;
       return { error: "Task not found" };
     }
+    console.error("Unhandled error:", msg);
     set.status = 500;
     return { error: "Internal server error" };
   })