diff --git a/src/Database/DBA.php b/src/Database/DBA.php
index d0a0bbe2f4..4eff592f09 100644
--- a/src/Database/DBA.php
+++ b/src/Database/DBA.php
@@ -223,7 +223,7 @@ class DBA
 	 * @return boolean Are there rows for that condition?
 	 * @throws \Exception
 	 */
-	public static function exists(string $table, array $condition): bool
+	public static function exists($table, array $condition): bool
 	{
 		return DI::dba()->exists($table, $condition);
 	}
diff --git a/view/theme/frio/style.php b/view/theme/frio/style.php
index b39cef1029..6d7e7b73f6 100644
--- a/view/theme/frio/style.php
+++ b/view/theme/frio/style.php
@@ -79,7 +79,7 @@ if (!empty($_REQUEST['scheme'])) {
 	$scheme = $_REQUEST['scheme'];
 }
 
-$scheme = Strings::sanitizeFilePathItem($scheme);
+$scheme = Strings::sanitizeFilePathItem($scheme ?? '');
 
 if (($scheme) && ($scheme != '---')) {
 	if (file_exists('view/theme/frio/scheme/' . $scheme . '.php')) {