[cleanup] Fix infodict returned fields (#8906)

Authored by: seproDev

yt_dlp/extractor/ondemandkorea.py

@@ -11,6 +11,7 @@ from ..utils import (
     join_nonempty,
     parse_age_limit,
     parse_qs,
+    str_or_none,
     unified_strdate,
     url_or_none,
 )
@@ -32,7 +33,7 @@ class OnDemandKoreaIE(InfoExtractor):
             'duration': 5486.955,
             'release_date': '20220924',
             'series': 'Ask Us Anything',
-            'series_id': 11790,
+            'series_id': '11790',
             'episode_number': 351,
             'episode': 'Jung Sung-ho, Park Seul-gi, Kim Bo-min, Yang Seung-won',
         },
@@ -47,7 +48,7 @@ class OnDemandKoreaIE(InfoExtractor):
             'duration': 1586.0,
             'release_date': '20231001',
             'series': 'Breakup Probation, A Week',
-            'series_id': 22912,
+            'series_id': '22912',
             'episode_number': 8,
             'episode': 'E08',
         },
@@ -117,7 +118,7 @@ class OnDemandKoreaIE(InfoExtractor):
                 'duration': ('duration', {functools.partial(float_or_none, scale=1000)}),
                 'age_limit': ('age_rating', 'name', {lambda x: x.replace('R', '')}, {parse_age_limit}),
                 'series': ('episode', {if_series(key='program')}, 'title'),
-                'series_id': ('episode', {if_series(key='program')}, 'id'),
+                'series_id': ('episode', {if_series(key='program')}, 'id', {str_or_none}),
                 'episode': ('episode', {if_series(key='title')}),
                 'episode_number': ('episode', {if_series(key='number')}, {int_or_none}),
             }, get_all=False),