[utils] Fix `PagedList`

yt_dlp/utils.py

@@ -4179,7 +4179,9 @@ class PagedList:
         self._cache = {}
 
     def getpage(self, pagenum):
-        page_results = self._cache.get(pagenum) or list(self._pagefunc(pagenum))
+        page_results = self._cache.get(pagenum)
+        if page_results is None:
+            page_results = list(self._pagefunc(pagenum))
         if self._use_cache:
             self._cache[pagenum] = page_results
         return page_results
@@ -4195,7 +4197,9 @@ class PagedList:
         if not isinstance(idx, int) or idx < 0:
             raise TypeError('indices must be non-negative integers')
         entries = self.getslice(idx, idx + 1)
-        return entries[0] if entries else None
+        if not entries:
+            raise IndexError()
+        return entries[0]
 
 
 class OnDemandPagedList(PagedList):