Ensure teardown is always called, use a shutdown function

Also add a flag in Media to be able to distinguish request types,
which is useful when logging.

lib/Skeleton/Core/Application.php

@@ -123,10 +123,12 @@ public function accept(): void {
 		\Skeleton\Core\Application::set($this);
 
 		$continue = $this->call_event('application', 'bootstrap', []);
+
+		register_shutdown_function([$this, 'call_event'], 'application', 'teardown', []);
+
 		if ($continue) {
 			$this->run();
 		}
-		$this->call_event('application', 'teardown', []);
 	}
 
 	/**

lib/Skeleton/Core/Http/Media.php

@@ -80,6 +80,13 @@ class Media {
 		],
 	];
 
+	/**
+	 * Flag to register whether media was served or not
+	 *
+	 * @access protected
+	 */
+	protected static bool $served = false;
+
 	/**
 	 * Constructor
 	 *
@@ -116,6 +123,8 @@ public function has_known_extension(): bool {
 	 * @access public
 	 */
 	public function serve(): void {
+		self::$served = true;
+
 		// Send the Etag before potentially replying with 304
 		header('Etag: ' . crc32((string)$this->get_mtime()) . '-' . sha1($this->get_path()));
 		$this->http_if_modified();
@@ -124,6 +133,15 @@ public function serve(): void {
 		exit;
 	}
 
+	/**
+	 * Has media been served?
+	 *
+	 * @access public
+	 */
+	public static function is_served(): bool {
+		return self::$served;
+	}
+
 	/**
 	 * Detect if the request is a request for media
 	 *