Try patching events-manager/classes/em-event.php with the folling:
583c583,587
< $event_truly_exists = $wpdb->get_var('SELECT event_id FROM '.EM_EVENTS_TABLE." WHERE event_id={$this->event_id}") == $this->event_id;
---
> if (empty($this->event_id)) {
> $event_truly_exists = false;
> } else {
> $event_truly_exists = $wpdb->get_var('SELECT event_id FROM '.EM_EVENTS_TABLE." WHERE event_id={$this->event_id}") == $this->event_id;
> }
The error is raising when the event_id property of the EM_Event object is empty, and so the query fails.
