Why there is a second title "yii\base\ErrorException" on the pages of the site?

On some pages of the website were 2 title.

The second title to the following:
yii\base\ErrorException

While in the source code of the second title no. There is a program for parsing. They scan the website, by analogy with the search engines. What can be the reason?

code where connect meta tags to the header

<?= Html::csrfMetaTags() ?>

he meta title tag, which is generated for the page
$this->registerMetaTag([
 'property' => 'og:title',
 'content' => $this->title
]);