Почему ошибка при запуске?

var maxName = null;
var max = 0; 
var salaries = {
  "John": 100,
  "Pete": 300,
  "Mary": 250
};
console.log(maxName);
(function topSalary() {  
    for(const [name, salary] of Object.entries(salaries)) {
      if (max < salary) {
        max = salary;
        maxName = name;
      }
    } 
    return maxName;
  })()
console.log(maxName);