oh joy! it's a MethodInvocationException!

Message: Invocation of method 'getVehicleId' in class gr.netmechanics.platform.rentacar.site.BookingHelper$Proxy$_$$_WeldClientProxy threw exception java.lang.NullPointerException at WEB-INF/vm/page/booking_step5.vm[line 32, column 60]

Reference name: BOOKING_HELPER

Method name: getVehicleId