anchor.diff:  
     function handleExpenseError(error) {
       resetErrors();
  +    addErrors(JSON.parse(error.responseText).error);
  +  }
  +
  +  function addErrors(errors) {
       $('#error_message').text("Please enter valid information.");
  -    errors = JSON.parse(error.responseText).error;
       for (var j = 0; j < errors.length; j++) {
         var error = errors[j];
         $('#error_list').append('<li>' + error + '</li>');
  
positive.code:     updateCategory(category);
      resetExpense();
      resetErrors();
  
      var expenses = category.expenses
      for (var i = 0; i < expenses.length; i++) {
        var expense = expenses[i];
        addExpenseRow(expense);
      }
    }
  
    function updateCategory(category) {
  
negative.code:     $('form')[0].reset();
    }
  
    function fillExpenseTable(category) {
      var expenses = category.expenses
      for (var i = 0; i < expenses.length; i++) {
        var expense = expenses[i];
        addExpenseRow(expense);
      }
    }
  
    function addExpenseRow(expense) {
      var description = '<th scope="row">' + expense.description + '</th>';
      var percentage = '<td>' + expense.percentage() + '%</td>';
  