Python使用pickle模块报错EOFError Ran out of input的解决方法

# coding=utf-8
import pickle
def usr_date():
  try:
    with open('usr_date.pkl','rb') as f:
      return pickle.load(f)
  except EOFError: #捕获异常EOFError 后返回None
    return None
def update_usr(usr_dic):
  with open('usr_date.pkl','wb') as f:
     pickle.dump(usr_dic,f)
def register():
  '注册'
  usr_dic = {}
  usr_name = input('请输入用户名')
  open_date = usr_date() if usr_date() else {}
  if usr_name in open_date.keys():
    print('用户已存在，请登录')
    return False
  usr_password = input('请输入你的密码：')
  usr_dic[usr_name] = usr_password
  update_usr(usr_dic)
  return print('注册成功')
def Sign_in():
  '登录'
  pass
def login_index():
  while True:
    usr = input('1.注册 2.登录 0.退出')
    if usr == '1':
      register()
    elif usr =='2':
      Sign_in()
    else:
      break