diff --git a/yt_dlp/YoutubeDL.py b/yt_dlp/YoutubeDL.py
index 7af7a9fb9..d4f8d8cab 100644
--- a/yt_dlp/YoutubeDL.py
+++ b/yt_dlp/YoutubeDL.py
@@ -2237,7 +2237,7 @@ def selector_function(ctx):
                         matches = LazyList(_check_formats(matches[::-1 if format_reverse else 1]))
                         try:
                             yield matches[format_idx - 1]
-                        except IndexError:
+                        except LazyList.IndexError:
                             return
 
             filters = [self._build_format_filter(f) for f in selector.filters]
diff --git a/yt_dlp/utils.py b/yt_dlp/utils.py
index 84b2603df..ba9566cab 100644
--- a/yt_dlp/utils.py
+++ b/yt_dlp/utils.py
@@ -778,7 +778,7 @@ def sanitize_path(s, force=False):
         for path_part in norm_path]
     if drive_or_unc:
         sanitized_path.insert(0, drive_or_unc + os.path.sep)
-    elif force and s[0] == os.path.sep:
+    elif force and s and s[0] == os.path.sep:
         sanitized_path.insert(0, os.path.sep)
     return os.path.join(*sanitized_path)