Ошибка "Индексу не присвоено значение" при удалении из DataGridView

using System;
using System.Collections.Generic;
using System.Windows.Forms;
using DataLayer;
using Zadanie3.Dialogs;
using Zadanie3.Interfaces;
 
namespace Zadanie3
{
    public partial class EmployeesForm : Form, IGiveRaise, IAddNewEmployee
    {
        
        private readonly List<Employee> _employeesData;
 
        public EmployeesForm()
        {
            InitializeComponent();
            EmployeesGridView.DataSource = _employeesData = EmployeesData.GetEmployees();
            
        }
 
        public void AddNewEmployee(string firstName, string lastName, DateTime birthdate, int salary)
        {
          
            
            var newEmployee = new Employee
            {
                IdEmployee = _employeesData.Count+1,
                FirstName = firstName,
                LastName = lastName,
                Birthdate = birthdate.Date,
                Salary = salary
            };
 
            _employeesData.Add(newEmployee);
            (EmployeesGridView.BindingContext[EmployeesGridView.DataSource] as CurrencyManager).Refresh();
        }
 
        public void GiveRaise(int percent)
        {
            foreach (DataGridViewRow selectedRow in EmployeesGridView.SelectedRows)
            {
                var employee = (Employee) selectedRow.DataBoundItem;
                if (employee.Salary == null)
                {
                    employee.Salary = 0;
                    employee.Salary = employee.Salary + (int)(employee.Salary * (percent / 100.0));
                }else employee.Salary = employee.Salary + (int) (employee.Salary*(percent/100.0));
            }
            EmployeesGridView.Refresh();
        }
 
        private void GiveRaiseButton_Click(object sender, EventArgs e)
        {
            var dialog = new GiveRaiseDialog(this);
            dialog.ShowDialog();
        }
 
        private void AddButton_Click(object sender, EventArgs e)
        {
            var dialog = new AddEmployeeDialog(this);
            dialog.ShowDialog();
        }
 
        private void DeleteButton_Click(object sender, EventArgs e)
        {
            foreach (DataGridViewRow selectedRow in EmployeesGridView.SelectedRows)
            {
                var employee = (Employee) selectedRow.DataBoundItem;
               
                _employeesData.Remove(employee);
                
 
 
            }
        }
 
        private void EmployeesGridView_CellContentClick(object sender, DataGridViewCellEventArgs e)
        {
 
        }
    }
}