with the keyboard navigation I select a event which is longer then the scheduler view port, example: view port of the month november and the event is from 15 oct until 15 dec.
when I then use the arrow left key I get a error (see attachment)
This bug should be fixed now in the latest sandbox build (2023.4.5786):
https://release.daypilot.org/changes/js/
Please let me know if the problem persists.