Any employer engaged in manufacturing that requires its employees, under penalty of forfeiture of a part of the wages earned by those employees, to provide a notice of intention to leave the employer’s employ shall be liable for the payment of a like forfeiture if the employer discharges, without similar notice, an employee, other than for incapacity or misconduct, except in case of a general suspension of labor in the employer’s shop or factory or in the department of the employer’s shop or factory in which the employee is employed.