code: def test_load_custom_model_fail(self):
      try:
          aug = nac.KeyboardAug(
              model_path="test_load_custom_model_fail.json"
          )
          self.assertTrue(False)
      except ValueError:
          self.assertTrue(True)
  
imports: import unittest
  import re
  import json
  import os
  import nlpaug.augmenter.char
label_desc: Use image node_id 16 for calling the TestKeyboard obj's underlying member method code with example usage: obj.test_load_custom_model_fail() without return types