Small plugin to make a ticket required by removing the 0 ticket option.

eeticketremover.php

<?php
/*
Plugin Name: EE add JavaScript to make ticket required.
Description: 
*/
/* Begin Adding Functions Below This Line */


function ee_1() {

	if(is_singular('espresso_events')) {
		?>
		<script type="text/javascript">
		jQuery(document).ready(function() {

			//Change the ID (ticket-selector-tbl-qty-slct-1680-1 in this case) to match the correct ticket.
			jQuery('#ticket-selector-tbl-qty-slct-1680-1 option[value="0"]').remove(); 

		});
		</script>
<?php
	}
}
add_action('wp_footer', 'ee_1', 100);