Fix typo in docblock

src/Monolog/Handler/StreamHandler.php

@@ -28,10 +28,10 @@ class StreamHandler extends AbstractProcessingHandler
     protected $filePermission;
 
     /**
-     * @param string  $stream
-     * @param integer $level           The minimum logging level at which this handler will be triggered
-     * @param Boolean $bubble          Whether the messages that are handled can bubble up the stack or not
-     * @param int     $filePermissions Optional file permissions (default (0644) are only for owner read/write)
+     * @param string   $stream
+     * @param integer  $level          The minimum logging level at which this handler will be triggered
+     * @param Boolean  $bubble         Whether the messages that are handled can bubble up the stack or not
+     * @param int|null $filePermission Optional file permissions (default (0644) are only for owner read/write)
      */
     public function __construct($stream, $level = Logger::DEBUG, $bubble = true, $filePermission = null)
     {