Widget\Base\Contents::___title(): Return value must be of type string, null returned
TypeError: Widget\Base\Contents::___title(): Return value must be of type string, null returned in /app/var/Widget/Base/Contents.php:551
Stack trace:
#0 /app/var/Typecho/Widget.php(462): Widget\Base\Contents->___title()
#1 /app/usr/themes/TypechoGlass/functions.php(559): Typecho\Widget->__get('title')
#2 /app/usr/themes/TypechoGlass/header.php(6): ag_document_title(Object(Widget\Archive))
#3 /app/var/Widget/Archive.php(1308): require('/app/usr/themes...')
#4 /app/usr/themes/TypechoGlass/archive.php(4): Widget\Archive->need('header.php')
#5 /app/var/Widget/Archive.php(1390): require_once('/app/usr/themes...')
#6 /app/var/Typecho/Router.php(88): Widget\Archive->render()
#7 /app/index.php(23): Typecho\Router::dispatch()
#8 {main}