Hi,
you have a missing use statement in \Bednarik\Cooluri\Integration\CoolPageResolver. When a backend user is viewing a page in the frontend, that he doesn't have access an exception is thrown because of that.
The error is in this line:
$this->setBackendUserAspect(\TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(Context::class), null); (line 66 in version 1.2.2)
It can be resolved by adding this statement below the namespace:
use TYPO3\CMS\Core\Context\Context;