修复图片地址获取失败问题

src/server/utils/new_oss_client.py

@@ -80,7 +80,7 @@ def get_presigned_url(oss_client, bucket, object_name):
         return presigned_url
     except Exception as e:
         print(f"get_presigned_url exception :{e}")
-        return "object not found"
+        return None
 
 
 def is_minio_file_exist(oss_client: Minio, bucket_name: str, object_name: str) -> bool:
@@ -120,4 +120,4 @@ if __name__ == '__main__':
     img.show()
     img.save("result.png")
     # get_presigned_url(oss_client=minio_client, bucket="fida-test", object_name="furniture/sketches/07bf4cfe-4502-4821-b78f-7727bf409498.png")
-#
+#