preview load timeout fix 2

backend/config_parser.py

@@ -301,9 +301,14 @@ class TranscodeTools:
                         async for chunk in nvr.stream_file(file, preview_pre_bytes):
                             await raw.write(chunk)
             except asyncio.TimeoutError as te:
+                try:
                     idx = self.preview_storage.index(preview_file)
                     del self.preview_storage[idx]
+                except:
+                    self.preview_storage = []
+
                 self.logger.info(f"Cancel download file: {te}")
+                if os.path.exists(raw_file):
                     os.remove(raw_file)
             finally:
                 nvr.logout()