When no events, template code produces closing ul tag

Hopefully this will save some people from pulling their hair out. I, on the other hand, am going bald.

When using the template code to list events in a theme, the code will output a closing ul tag when no events are available.
Why? I have no idea.

Here’s the code I used to respond to an empty calendar:

<?php
if (function_exists('scheduler_sidebar')) {
	$list_of_events = scheduler_sidebar();
	if($list_of_events == '</ul>') {/* the scheduler plugin outputs a '</ul>' when there are no events */
        $message = 'No events scheduled at this time';
        echo ('<ul><li>'.$message'.</li></ul>');
	} else {
	    echo $list_of_events; //outputs an unordered list
}}?>