input: Write a function to implement a basic REST API using Python and Flask to list all the countries in the world. The API should read the list of countries from a JSON file and return it as a JSON response. If the file is empty or the file does not exist, return an empty list.
  
  assert get_countries() == [{'name': 'Afghanistan', 'code': 'AF'}, {'name': 'Albania', 'code': 'AL'}, ...]
  assert get_countries() == []
  assert get_countries() == [{'name': 'Canada', 'code': 'CA'}, {'name': 'Mexico', 'code': 'MX'}, ...]
output: 
  def get_countries():
      try:
          with open('countries.json', 'r') as file:
              data = json.load(file)
              return data if data else []
      except (FileNotFoundError, json.JSONDecodeError):
          return []
  