fix exam grading

src/pages/grading/ParticipationPage.tsx

@@ -5,6 +5,10 @@ import { fetchParticipation, postParticipation } from '../../api/grading'
 import { GRADING_PATH } from './gradingPaths'
 
 /** CI `grading/participation.php` */
+function normalizeParticipationScore(value: unknown): number | string | null {
+  return typeof value === 'number' || typeof value === 'string' ? value : null
+}
+
 export function ParticipationPage() {
   const [searchParams] = useSearchParams()
   const [rows, setRows] = useState<
@@ -17,7 +21,7 @@ export function ParticipationPage() {
     }>
   >([])
   const [locked, setLocked] = useState(false)
-  const [title, setTitle] = useState('Participation Scores')
+  const [title] = useState('Participation Scores')
   const [sectionName, setSectionName] = useState('')
   const [semester, setSemester] = useState(searchParams.get('semester') ?? '')
   const [schoolYear, setSchoolYear] = useState(searchParams.get('school_year') ?? '')
@@ -46,7 +50,7 @@ export function ParticipationPage() {
                 school_id: typeof student.school_id === 'string' ? student.school_id : null,
                 firstname: typeof student.firstname === 'string' ? student.firstname : null,
                 lastname: typeof student.lastname === 'string' ? student.lastname : null,
-                score: scores.score ?? null,
+                score: normalizeParticipationScore(scores.score),
               }
             }),
           )
@@ -112,7 +116,7 @@ export function ParticipationPage() {
               school_id: typeof student.school_id === 'string' ? student.school_id : null,
               firstname: typeof student.firstname === 'string' ? student.firstname : null,
               lastname: typeof student.lastname === 'string' ? student.lastname : null,
-              score: scores.score ?? null,
+              score: normalizeParticipationScore(scores.score),
             }
           }),
         )