code: def test_non_existent_backbone():
      with pytest.raises(KeyError):
          ImageClassifier(
              2, backbone="i am never going to implement this lol"
          )
  
imports: from typing import Any
  from unittest.mock import patch
  import pytest
  import torch
  from flash import Trainer
  from flash.core.data.io.input import DataKeys
  from flash.core.utilities.imports import _TOPIC_IMAGE_AVAILABLE, _TOPIC_SERVE_AVAILABLE
  from flash.image import ImageClassifier
  from torch import Tensor
  from tests.helpers.task_tester import TaskTester
label_desc: Use image node_id 1 for calling a global function with example usage: test_non_existent_backbone() without return types