Cannot create new client without email

Hi,

I wrote to you on other problems concerning the import of clients and sends them emails and grants them access to WordPress.

So now I was creating some reservations by hand and at same time creating new customers. I did it for a few without emails but then about the 5th customer I create I got an message in read saying that email field could not be empty and then I got a white screen with the following error:

PS It should be possible to create users and bookings without emails. And I wrote before also that booking done by hand in Google calendar will not push the other way and get blocked in time. They must be created in the software. If that is the case then we have to at least be able to create users without email since we are booking them by phone but still need to block the time.

Fatal error: Uncaught Error: __clone method called on non-object in /home3/karras/esthetiquemterry.com/wp-content/plugins/salon-booking-system/src/SLN/Wrapper/Booking/Service.php:102 Stack trace: #0 /home3/karras/esthetiquemterry.com/wp-content/plugins/salon-booking-system/src/SLN/Third/GoogleScope.php(734): SLN_Wrapper_Booking_Service->getEndsAt() #1 /home3/karras/esthetiquemterry.com/wp-content/plugins/salon-booking-system/src/SLN/Third/GoogleScope.php(634): SLN_GoogleCalendarEventFactory->get_event(Object(SLN_Wrapper_Booking)) #2 /home3/karras/esthetiquemterry.com/wp-content/plugins/salon-booking-system/src/SLN/Third/GoogleScope.php(830): SLN_GoogleScope->create_event_from_booking(Object(SLN_Wrapper_Booking)) #3 /home3/karras/esthetiquemterry.com/wp-includes/class-wp-hook.php(288): synch_a_booking(1408, Object(WP_Post)) #4 /home3/karras/esthetiquemterry.com/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters(NULL, Array) #5 /home3/karras/esthetiquemterry.com/wp-includes/plugin.php(453): WP_Hook->do_action(Array) in /home3/karras/esthetiquemterry.com/wp-content/plugins/salon-booking-system/src/SLN/Wrapper/Booking/Service.php on line 102