Improve unfound valid image text

Author: iMattPro

event/listener.php

@@ -64,7 +64,7 @@ class listener implements EventSubscriberInterface
 	 * @param template $template Template object
 	 * @param user $user
 	 * @param manager $phpbb_notifications Notifications manager object
-	 * @param $root_path
+	 * @param string $root_path
 	 */
 	public function __construct(config $config, controller_helper $controller_helper, FastImageSize $imagesize, form_helper $form_helper, language $language, template $template, user $user, manager $phpbb_notifications, $root_path)
 	{

language/en/webpushnotifications_common_acp.php

@@ -48,6 +48,6 @@
 	'PWA_ICON_LARGE_EXPLAIN'	=> 'File name of a 512px x 512px PNG image. This file must be uploaded to your board’s <samp>' . \phpbb\webpushnotifications\ext::PWA_ICON_DIR . '</samp> directory.',
 	'PWA_ICON_SIZE_INVALID'		=> '“%s” does not have the correct image dimensions.',
 	'PWA_ICON_MIME_INVALID'		=> '“%s” must be a PNG image file.',
-	'PWA_IMAGE_INVALID'			=> '“%s” does not appear to be a valid image file.',
+	'PWA_IMAGE_INVALID'			=> '“%s” does not appear to be a valid image file. Verify the file name and location are correct.',
 	'PWA_IMAGE_NOT_PROVIDED'	=> '%s field must not be empty. All icon fields must contain an image.',
 ]);