Update app.py

app.py

@@ -356,7 +356,7 @@ class HRCollectorVideoProcessor:
 
     def stop_and_dump_to_file(self) -> Optional[str]:
         self.recording = False
-               if len(self.frames) < 30:  # ~1s
+        if len(self.frames) < 30:  # ~1s
             return None
         h, w = self.frames[0].shape[:2]
         fourcc = cv2.VideoWriter_fourcc(*"mp4v")