refactor(views): use react-query's isLoadingError instead of reimplementing it

deriveQueryStatus previously inferred "never received data" by checking
data !== undefined itself. TanStack Query already computes and exposes
this exact distinction as isLoadingError (isError && no data) vs
isRefetchError (isError && data present) on every useQuery result, so
consume that directly instead of duplicating the logic.

apps/client/src/common/hooks-query/useCustomFields.ts

@@ -9,12 +9,12 @@ import { deriveQueryStatus } from '../utils/queryUtils';
 const placeholder: CustomFields = {};
 
 export default function useCustomFields() {
-  const { data, status, isFetching, isError, refetch } = useQuery({
+  const { data, status, isFetching, isError, isLoadingError, refetch } = useQuery({
     queryKey: CUSTOM_FIELDS,
     queryFn: ({ signal }) => getCustomFields({ signal }),
     placeholderData: (previousData, _previousQuery) => previousData,
     refetchInterval: queryRefetchIntervalSlow,
   });
 
-  return { data: data ?? placeholder, status: deriveQueryStatus(status, data), isFetching, isError, refetch };
+  return { data: data ?? placeholder, status: deriveQueryStatus(status, isLoadingError), isFetching, isError, refetch };
 }

apps/client/src/common/hooks-query/useProjectData.ts

@@ -7,14 +7,20 @@ import { projectDataPlaceholder } from '../models/ProjectData';
 import { deriveQueryStatus } from '../utils/queryUtils';
 
 export default function useProjectData() {
-  const { data, status, isFetching, isError, refetch } = useQuery({
+  const { data, status, isFetching, isError, isLoadingError, refetch } = useQuery({
     queryKey: PROJECT_DATA,
     queryFn: ({ signal }) => getProjectData({ signal }),
     placeholderData: (previousData, _previousQuery) => previousData,
     refetchInterval: queryRefetchIntervalSlow,
   });
 
-  return { data: data ?? projectDataPlaceholder, status: deriveQueryStatus(status, data), isFetching, isError, refetch };
+  return {
+    data: data ?? projectDataPlaceholder,
+    status: deriveQueryStatus(status, isLoadingError),
+    isFetching,
+    isError,
+    refetch,
+  };
 }
 
 export function useUpdateProjectData() {

apps/client/src/common/hooks-query/useRundown.ts

@@ -33,7 +33,7 @@ export default function useRundown() {
     data: { loaded: loadedRundownId },
   } = useProjectRundowns();
 
-  const { data, status, isError, refetch, isFetching } = useQuery<Rundown>({
+  const { data, status, isError, isLoadingError, refetch, isFetching } = useQuery<Rundown>({
     queryKey: loadedRundownId ? getRundownQueryKey(loadedRundownId) : CURRENT_RUNDOWN_QUERY_KEY,
     queryFn: ({ signal }) => fetchCurrentRundown({ signal }),
     refetchInterval: queryRefetchIntervalSlow,
@@ -51,7 +51,13 @@ export default function useRundown() {
     queryClient.removeQueries({ queryKey: CURRENT_RUNDOWN_QUERY_KEY, exact: true });
   }, [loadedRundownId, queryClient]);
 
-  return { data: data ?? cachedRundownPlaceholder, status: deriveQueryStatus(status, data), isError, refetch, isFetching };
+  return {
+    data: data ?? cachedRundownPlaceholder,
+    status: deriveQueryStatus(status, isLoadingError),
+    isError,
+    refetch,
+    isFetching,
+  };
 }
 
 export function useRundownWithMetadata() {
@@ -128,7 +134,7 @@ export function useRundownAuxData() {
 export function useRundownById(rundownId: string | null | undefined) {
   const enabled = Boolean(rundownId);
 
-  const { data, status, isError, refetch, isFetching } = useQuery<Rundown>({
+  const { data, status, isError, isLoadingError, refetch, isFetching } = useQuery<Rundown>({
     queryKey: getRundownQueryKey(rundownId ?? ''),
     queryFn: ({ signal }) => fetchRundown(rundownId!, { signal }),
     enabled,
@@ -136,5 +142,11 @@ export function useRundownById(rundownId: string | null | undefined) {
     refetchInterval: queryRefetchIntervalSlow,
   });
 
-  return { data: data ?? cachedRundownPlaceholder, status: deriveQueryStatus(status, data), isError, refetch, isFetching };
+  return {
+    data: data ?? cachedRundownPlaceholder,
+    status: deriveQueryStatus(status, isLoadingError),
+    isError,
+    refetch,
+    isFetching,
+  };
 }

apps/client/src/common/hooks-query/useSettings.ts

@@ -7,7 +7,7 @@ import { ontimePlaceholderSettings } from '../models/OntimeSettings';
 import { deriveQueryStatus } from '../utils/queryUtils';
 
 export default function useSettings() {
-  const { data, status, isFetching, isError, refetch } = useQuery({
+  const { data, status, isFetching, isError, isLoadingError, refetch } = useQuery({
     queryKey: APP_SETTINGS,
     queryFn: ({ signal }) => getSettings({ signal }),
     placeholderData: (previousData, _previousQuery) => previousData,
@@ -23,5 +23,11 @@ export default function useSettings() {
     },
   });
 
-  return { data: data ?? ontimePlaceholderSettings, status: deriveQueryStatus(status, data), isFetching, isError, refetch };
+  return {
+    data: data ?? ontimePlaceholderSettings,
+    status: deriveQueryStatus(status, isLoadingError),
+    isFetching,
+    isError,
+    refetch,
+  };
 }

apps/client/src/common/hooks-query/useViewSettings.ts

@@ -8,7 +8,7 @@ import { viewsSettingsPlaceholder } from '../models/ViewSettings.type';
 import { deriveQueryStatus } from '../utils/queryUtils';
 
 export default function useViewSettings() {
-  const { data, status } = useQuery({
+  const { data, status, isLoadingError } = useQuery({
     queryKey: VIEW_SETTINGS,
     queryFn: ({ signal }) => getViewSettings({ signal }),
     placeholderData: (previousData, _previousQuery) => previousData,
@@ -25,5 +25,5 @@ export default function useViewSettings() {
     },
   });
 
-  return { data: data ?? viewsSettingsPlaceholder, status: deriveQueryStatus(status, data), mutateAsync };
+  return { data: data ?? viewsSettingsPlaceholder, status: deriveQueryStatus(status, isLoadingError), mutateAsync };
 }

apps/client/src/common/utils/__tests__/queryUtils.test.ts

@@ -1,16 +1,14 @@
 import { deriveQueryStatus } from '../queryUtils';
 
 test('keeps pending and success statuses unchanged', () => {
-  expect(deriveQueryStatus('pending', undefined)).toBe('pending');
-  expect(deriveQueryStatus('success', { some: 'data' })).toBe('success');
+  expect(deriveQueryStatus('pending', false)).toBe('pending');
+  expect(deriveQueryStatus('success', false)).toBe('success');
 });
 
-test('keeps error status when there is no data', () => {
-  expect(deriveQueryStatus('error', undefined)).toBe('error');
+test('keeps error status on a genuine loading error (no data ever received)', () => {
+  expect(deriveQueryStatus('error', true)).toBe('error');
 });
 
-test('downgrades error to success when data is still available', () => {
-  expect(deriveQueryStatus('error', { some: 'data' })).toBe('success');
-  expect(deriveQueryStatus('error', [])).toBe('success');
-  expect(deriveQueryStatus('error', 0)).toBe('success');
+test('downgrades error to success on a refetch error (data still available)', () => {
+  expect(deriveQueryStatus('error', false)).toBe('success');
 });

apps/client/src/common/utils/queryUtils.ts

@@ -1,12 +1,13 @@
 import type { QueryStatus } from '@tanstack/react-query';
 
 /**
- * A background refetch failure still leaves the last successfully fetched data in place.
- * In that case we want callers to keep treating the query as usable rather than erroring out,
- * so we only report 'error' when we have never received data for this query.
+ * A background refetch failure (react-query's isRefetchError) still leaves the last
+ * successfully fetched data in place, so we want callers to keep treating the query as
+ * usable rather than erroring out. Only a genuine isLoadingError (never received data)
+ * should surface as 'error'.
  */
-export function deriveQueryStatus(status: QueryStatus, data: unknown): QueryStatus {
-  if (status === 'error' && data !== undefined) {
+export function deriveQueryStatus(status: QueryStatus, isLoadingError: boolean): QueryStatus {
+  if (status === 'error' && !isLoadingError) {
     return 'success';
   }
   return status;