Move validation of the channel ids from _register() to _subscribe()

ytnoti/base.py

@@ -365,6 +365,13 @@ async def _subscribe(self, channel_ids: str | Iterable[str]) -> None:
         if isinstance(channel_ids, str):
             channel_ids = [channel_ids]
 
+        async with AsyncClient() as client:
+            for channel_id in channel_ids:
+                response = await client.head(f"https://www.youtube.com/channel/{channel_id}")
+
+                if response.status_code != HTTPStatus.OK.value:
+                    raise ValueError(f"Invalid channel ID: {channel_id}")
+
         if not self.is_ready:
             self._subscribed_ids.update(channel_ids)
             return
@@ -388,13 +395,6 @@ async def _register(self,
         :raises HTTPError: If failed to subscribe or unsubscribe due to an HTTP error.
         """
 
-        async with AsyncClient() as client:
-            for channel_id in channel_ids:
-                response = await client.head(f"https://www.youtube.com/channel/{channel_id}")
-
-                if response.status_code != HTTPStatus.OK.value:
-                    raise ValueError(f"Invalid channel ID: {channel_id}")
-
         for channel_id in channel_ids:
             async with AsyncClient() as client:
                 self.__logger.debug("Sending %s request for channel: %s", mode, channel_id)