Wordpress: Check if the_content is empty / return custom text only when the_content is empty

Wordpress_text_for_empty_content.php

// Check if the content is empty and show a custom message //
add_filter('the_content', 'text_for_empty_content', 20, 1);
function text_for_empty_content($content){
    if(empty($content)) // Check if the content is empty
			return '<p>Under Construction</p>'; // Add your custom text or other HTML
		else
			return $content; // if content is there, just leave it as it is
}

/*
Developer Notes:
When you do this check using get_the_content() - the_content() filter will not work.

As the content does not pass through the_content filter, action filters from other plugins / theme will not work.

To avoid this, use the above mentioned hook and customize it to your needs

Works in WordPress 5+, PHP 7

*/