DB_CONNECTION=sqlite
DB_HOST=127.0.0.1
DB_PORT=3306
DB_DATABASE=database
DB_USERNAME=homestead
DB_PASSWORD=secret

public function index()
{
    // cause of the error
    $cards = Card::all();

    return view('cards.index', compact('cards'));
}

'database' => env('DB_DATABASE', database_path('database.sqlite')),

dd(env('DB_DATABASE'))               // => 'database/database.sqlite'
dd(database_path('database.sqlite')) // => 'D:wwwprojectdatabasedatabase.sqlite'

'database' => env('DB_DATABASE', database_path('database.sqlite')),

'database' => database_path('database.sqlite'),

DB_DATABASE=..databasedatabase.sqlite

DB_DATABASE=D:wwwprojectdatabasedatabase.sqlite

DB_DATABASE=databasedatabase.sqlite

'database' => env('DB_DATABASE/..', database_path('database.sqlite')),

'database' => env('DB_DATABASE', database_path('database.sqlite'))

'database' => database_path(env('DB_DATABASE'))

DB_DATABASE=/var/www/project/database/database.sqlite

DB_DATABASE=D:wwwprojectdatabasedatabase.sqlite

DB_CONNECTION=mysql
DB_HOST=127.0.0.1
DB_PORT=3306
DB_DATABASE=homestead
DB_USERNAME=homestead
DB_PASSWORD=secret

DB_CONNECTION=sqlite
DB_DATABASE=/absolute/path/to/database.sqlite

'connections' => [

    'sqlite_testing' => [
        'driver' => 'sqlite',
        'database' => database_path('testing-db.sqlite'),
        'prefix' => '',
    ],

    ...
]