修正两处notice

library/think/Input.php

@@ -288,6 +288,9 @@ class Input
      */
     private static function regexFilter($input, $filter)
     {
+        if(empty($filter_)){
+            return null;
+        }
         $begin = $filter[0];
         $end   = $filter[strlen($filter) - 1];
         if (is_array($input)) {

library/think/Route.php

@@ -19,6 +19,7 @@ class Route
         'POST'   => [],
         'PUT'    => [],
         'DELETE' => [],
+        'HEAD'   => [],
         '*'      => [],
     ];