more flexible suffix check

cbz/comic.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import logging
 import zipfile
 
 from datetime import datetime, timezone
@@ -172,8 +173,13 @@ class ComicInfo(ComicModel):
         pages_info = comic_info.get('Pages', {}).get('Page', [])
         for i, name in enumerate(names):
             suffix = Path(name).suffix
-            if suffix:
-                assert suffix in IMAGE_FORMAT, f'Unsupported image format: {suffix}'
+
+            # Some archives may contain folders or hidden files (e.g., ".extra/" or "__MACOSX/.DS_Store")
+            # that could corrupt the suffix detection and cause invalid image handling.
+            if not suffix or suffix not in IMAGE_FORMAT:
+                logging.warning(f'Skipping unsupported or invalid file: {name!r} (suffix={suffix!r})')
+                continue
+
             with archive_file.open(name, 'r') as f:
                 page_info = {}
                 if i < len(pages_info):