fix(review): address Greptile P2 findings

- test: add group_by_mock.assert_awaited_once() before await_args access
  so a non-call produces a clear AssertionError rather than AttributeError
- ui: wrap tagListCall IIFE in try/catch; log error on failure instead of
  silently leaving the tag dropdown stale

Co-Authored-By: Claude Sonnet 4 (1M context) <noreply@anthropic.com>

tests/test_litellm/proxy/management_endpoints/test_tag_management_endpoints.py

@@ -445,6 +445,7 @@ async def test_list_tags_without_date_range_omits_date_filter():
             response = client.get("/tag/list", headers=headers)
 
             assert response.status_code == 200
+            group_by_mock.assert_awaited_once()
             where = group_by_mock.await_args.kwargs["where"]
             assert "date" not in where
 

ui/litellm-dashboard/src/components/UsagePage/components/UsagePageView.tsx

@@ -162,14 +162,20 @@ const UsagePage: React.FC<UsagePageProps> = ({ teams, organizations }) => {
     if (!accessToken) return;
     let cancelled = false;
     (async () => {
-      const tags = await tagListCall(accessToken, startTime, endTime);
-      if (cancelled) return;
-      setAllTags(
-        Object.values(tags).map((tag: Tag) => ({
-          label: tag.name,
-          value: tag.name,
-        })),
-      );
+      try {
+        const tags = await tagListCall(accessToken, startTime, endTime);
+        if (cancelled) return;
+        setAllTags(
+          Object.values(tags).map((tag: Tag) => ({
+            label: tag.name,
+            value: tag.name,
+          })),
+        );
+      } catch (e) {
+        if (!cancelled) {
+          console.error("Failed to fetch tag list", e);
+        }
+      }
     })();
     return () => {
       cancelled = true;