fix: add error state handling for checklist query

client/src/pages/admin-test-checklist/ui/AdminTestChecklistPage.tsx

@@ -1,4 +1,5 @@
 import { useMemo, useState } from 'react'
+import Alert from '@mui/material/Alert'
 import Accordion from '@mui/material/Accordion'
 import AccordionDetails from '@mui/material/AccordionDetails'
 import AccordionSummary from '@mui/material/AccordionSummary'
@@ -39,7 +40,7 @@ export function AdminTestChecklistPage() {
   const [confirmOpen, setConfirmOpen] = useState(false)
   const [expanded, setExpanded] = useState<string | false>(false)
 
-  const { data, isLoading } = useQuery({
+  const { data, isLoading, isError } = useQuery({
     queryKey: ['admin', 'test-checklist'],
     queryFn: fetchTestChecklistResults,
   })
@@ -94,6 +95,8 @@ export function AdminTestChecklistPage() {
         <Box sx={{ display: 'flex', justifyContent: 'center', py: 8 }}>
           <CircularProgress />
         </Box>
+      ) : isError ? (
+        <Alert severity="error">Не удалось загрузить чеклист.</Alert>
       ) : (
         sections.map(([section, items]) => (
           <Accordion key={section} expanded={expanded === section} onChange={(_, isExpanded) => setExpanded(isExpanded ? section : false)}>