After https://github.com/odoo/odoo/pull/99386, clicking on the email button in calendar.event form view would give a traceback as it tried accessing event_id on a calendar.event record. This commit fixes this error as the object in the template already is an instance of calendar.event. task-3127534 closes odoo/odoo#109549 Signed-off-by: Arnaud Joset <arj@odoo.com>