input: Write a function to store and retrieve user data in a JSON file. The function should take a dictionary representing the user data, store it in a file named 'user_data.json', and provide a method to retrieve the data from the file. If the file does not exist, an appropriate error should be raised.
  
  assert store_user_data({"Name": "John", "Age": 25, "City": "New York"})==None
  assert get_user_data()=={"Name": "John", "Age": 25, "City": "New York"}
  assert store_user_data({"Name": "Jane", "Age": 30, "City": "Los Angeles"})==None
  assert get_user_data()=={"Name": "Jane", "Age": 30, "City": "Los Angeles"}
  assert store_user_data({"Name": "Sam", "Age": 22, "City": "San Francisco"})==None
  assert get_user_data()=={"Name": "Sam", "Age": 22, "City": "San Francisco"}
  assert store_user_data({})==None
  assert get_user_data()=={}
  assert store_user_data(None)==None
  assert get_user_data()==None
output: def store_user_data(user_data):
      with open('user_data.json', 'w') as file:
          json.dump(user_data, file)
  
  def get_user_data():
      try:
          with open('user_data.json', 'r') as file:
              return json.load(file)
      except FileNotFoundError:
          return None