Imperative sum function that mistakenly tries to use the arguments object like an Array.

es5-arguments-imperative-sum-error.js

var sum = function () {
  var result = 0;
  
  arguments.forEach(function(number) {
    result = result + number;
  });
  
  return result;
};

sum(1, 2, 3, 4, 5); // => "TypeError: arguments.forEach is not a function