input: Write a function to store and query user data. The function should accept a dictionary containing user data and store it in a JSON file. Another function should read and return the user data from the JSON file. If the JSON file doesn't exist, an appropriate message should be returned.
  
  import json
  
  user_data = {"Name": "John", "Age": 25, "City": "New York"}
  
  def store_user_data(data):
      try:
          with open('user_data.json', 'w') as f:
              json.dump(data, f)
          return "Data stored successfully."
      except Exception as e:
          return f"Error storing data: {e}"
  
  def get_user_data():
      try:
          with open('user_data.json') as f:
              return json.load(f)
      except FileNotFoundError:
          return "No data found."
      except Exception as e:
          return f"Error retrieving data: {e}"
  
  assert store_user_data(user_data) == "Data stored successfully."
  assert get_user_data() == {"Name": "John", "Age": 25, "City": "New York"}
  assert store_user_data({"Name": "Jane", "Age": 30, "City": "Los Angeles"}) == "Data stored successfully."
  assert get_user_data() == {"Name": "Jane", "Age": 30, "City": "Los Angeles"}
  assert store_user_data({}) == "Data stored successfully."
  assert get_user_data() == {}
  
output: 
  def store_user_data(data):
      try:
          with open('user_data.json', 'w') as f:
              json.dump(data, f)
          return "Data stored successfully."
      except Exception as e:
          return f"Error storing data: {e}"
  
  def get_user_data():
      try:
          with open('user_data.json') as f:
              return json.load(f)
      except FileNotFoundError:
          return "No data found."
      except Exception as e:
          return f"Error retrieving data: {e}"
  