[WordPress] Stop Plugin Execution Without a Dependency

00-constructor.php

<?php

public function __construct( $container ) {

	$this->can_run = true;

	// If the dependency isn't installed, then add a message and flag execution to stop.
	$this->messenger = $container->get( 'settings-messenger');
	if ( ! class_exists( 'Acme_Dependency' ) ) {

		$this->messenger->add_error_message( 'The dependency is not installed.' );
		$this->can_run = false;
	}
}

01-init.php

<?php

public function init() {

	if ( ! $this->can_run ) {
		return;
	}

	add_action( 'admin_notices', array( $this, 'admin_notices' ) );
}