This prevents a crash due to instance-config.php not existing, it will now check if the file exists and if not creates the file

install.php

@@ -3,6 +3,11 @@
 // Installation/upgrade file	
 define('VERSION', '4.9.93');
 
+if (fopen('inc/instance-config.php' , 'a') === false) {
+	print('install.php does not have permission to write to /inc/, without permission the installer cannot continue');
+	exit();
+	}
+
 require 'inc/functions.php';
 
 $step = isset($_GET['step']) ? round($_GET['step']) : 0;