Why doesn't AdminLTE Asset Bundle for yii2 redirect to login.php?

Question

Yii

Installed, did everything according to the instructions, compared with other sites that work for me, all one to one, but for some reason on one site when entering the backend
Gives an error
Trying to get property of non-object
on this line in backend/views/layouts /header.php

<span class="hidden-xs"><?= Yii::$app->user->identity->username; ?></span>

In principle, it is clear what the error is, since the user is not authorized and cannot be found.
But why doesn't it redirect to login.php?

Answer 1

1) Because it's a view. Manipulations with redirects should be done in the controller as much as possible. better in controller access rules.
2) <?= !Yii::$app->user->isGuest? Yii::$app->user->identity->username : ''; ?>