Fix some type errors detected by PHPStan

Signed-off-by: Maurício Meneghini Fauth <mauricio@fauth.dev>

1 files changed, 1 insertions, 1 deletions

diff --git a/setup/index.php b/setup/index.php
index 03e945d39f..76e0941db2 100644
--- a/setup/index.php
+++ b/setup/index.php
@@ -27,7 +27,7 @@ if (@file_exists(CONFIG_FILE) && ! $cfg['DBG']['demo']) {
     Core::fatalError(__('Configuration already exists, setup is disabled!'));
 }
 
-$page = Core::isValid($_GET['page'], 'scalar') ? (string) $_GET['page'] : null;
+$page = Core::isValid($_GET['page'], 'scalar') ? (string) $_GET['page'] : '';
 $page = preg_replace('/[^a-z]/', '', $page);
 if ($page === '') {
     $page = 'index';