Set default end-date as empty in new guest form

frontend/src/routes/sponsor/register/stepPersonForm.tsx

@@ -49,6 +49,7 @@ const StepPersonForm = forwardRef(
     const [todayPlusMaxDays, setTodayPlusMaxDays] = useState(today)
     const roleTypes = useRoleTypes()
     const { displayContactAtUnit, displayComment } = useContext(FeatureContext)
+    const [endDate, setEndDate] = useState<Date | null>(null)
 
     const roleTypeSort = () => (a: RoleTypeData, b: RoleTypeData) => {
       if (i18n.language === 'en') {
@@ -319,15 +320,16 @@ const StepPersonForm = forwardRef(
               <Controller
                 name="role_end"
                 control={control}
-                defaultValue={today}
                 render={({ field }) => (
                   <DatePicker
                     mask="____-__-__"
                     label={t('input.roleEndDate')}
+                    minDate={today}
                     maxDate={todayPlusMaxDays}
-                    value={field.value}
+                    value={endDate}
                     inputFormat="yyyy-MM-dd"
                     onChange={(value) => {
+                      setEndDate(value)
                       field.onChange(value)
                     }}
                     renderInput={(params) => <TextField {...params} />}