Too few arguments to function OSappscheduleInformation::showError()

See screenshot. After clicking `Remove time slot`, I get the following error:

0 Too few arguments to function OSappscheduleInformation::showError(), 3 passed in /components/com_osservicesbooking/classes/ajax.php on line 2679 and exactly 4 expected

Hi,
You can try this way to solve the problem
1. Open file: root > components > com_osservicesbooking > classes > information.php
2. Find:
function showError($sid,$eid,$errorArr,$vid){
and change to
function showError($sid,$eid,$errorArr,$vid = 0){
Good luck
Dam