Update app.py

app.py

@@ -401,7 +401,7 @@ if __name__ == "__main__":
         )
     except Exception as e:
         logger.error(f"Failed to parse BACKGROUNDS_DATA: {e}")
-        return None, None, None, None, None, None, None
+        return {}, {}, {}, {}, {}, {}, {}
 
 # 환경변수에서 배경 딕셔너리들 로드
 (SIMPLE_BACKGROUNDS, STUDIO_BACKGROUNDS, NATURE_BACKGROUNDS,