Installer does not display fatal errors that lead to extension check
When something breaks in the install tool - like update classes for example - the installer redirects you to the loaded extensions check. You have absolutely no clue why this happens.
On my machine an outdated devlog version caused the fatal as it tried to access the protected property TYPO3\CMS\Core\Database\DatabaseConnection::$link.
A box with the fatal that caused the check should be showed.