Laravel-log-viewer: Clave de índice de lumen indefinido

Lumen 5,8
Acabo de instalar su paquete pero obtengo:

(2/2) ErrorExceptionUndefined index: key (View: /app/vendor/rap2hpoutre/laravel-log-viewer/src/views/log.blade.php)
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in EncryptionServiceProvider.php line 42
at CompilerEngine->handleViewException(object(ErrorException), 0)in PhpEngine.php line 45
at PhpEngine->evaluatePath(


(1/2) ErrorExceptionUndefined index: key
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in EncryptionServiceProvider.php line 42
at Application->Laravel\Lumen\Concerns\{closure}(8, 'Undefined index: key', '/app/vendor/illuminate/encryption/EncryptionServiceProvider.php', 42, array('config' => array('aliases' => array('ReportRepository' => '\\App\\Repositories\\RawReportRepository', 'App' => 'Illuminate\\Support\\Facades\\App', 'Auth' => 'Illuminate\\Support\\Facades\\Auth', 'Bus' => 'Illuminate\\Support\\Facades\\Bus', 'DB' => 'Illuminate\\Support\\Facades\\DB', 'Cache' => 'Illuminate\\Support\\Facades\\Cache', 'Cookie' => 'Illuminate\\Support\\Facades\\Cookie', 'Crypt' => 'Illuminate\\Support\\Facades\\Crypt', 'Event' => 'Illuminate\\Support\\Facades\\Event', 'Hash' => 'Illuminate\\Support\\Facades\\Hash', 'Log' => 'Illuminate\\Support\\Facades\\Log', 'Mail' => 'Illuminate\\Support\\Facades\\Mail', 'Queue' => 'Illuminate\\Support\\Facades\\Queue', 'Request' => 'Illuminate\\Support\\Facades\\Request', 'Schema' => 'Illuminate\\Support\\Facades\\Schema', 'Session' => 'Illuminate\\Support\\Facades\\Session', 'Storage' => 'Illuminate\\Support\\Facades\\Storage', 'Eloquent' => 'Illuminate\\Database\\Eloquent\\Model'))))in EncryptionServiceProvider.php line 42